nRF5 action!

[mfalkvidd]

@NeverDie it seems like the preamble can be configured to be either 8 or 16 bits. Not sure if that's of any use, but I've been thinking about adjusting the LoRa preamble to get better sleep times. Maybe that could be applicable for nrf as well.

[NeverDie]

It turns out that using just the standard radiohead packet/frame structure, I'm able to 100% reliably receive a two byte string (in this case, the letter "H" followed by a zero as the termination character) using the above PPI solution with a receive window of about 200ms. That includes preamble, CRC, and a long network ID number.

I'm pleased with that result. It's vastly better than without the PPI solution.

[NeverDie]

OK, I'm going to start with this, which works:

//A simplified re-mix of code mostly written by d00616

#include <nrf.h>
#include <MySensors.h>

int interrupt = 0;
uint32_t theCounter;


int8_t myHwSleep(unsigned long ms)
{
  hwSleepPrepare(ms);
  //while (nrf5_rtc_event_triggered == false) {
    hwSleep();
  //}
  hwSleepEnd(ms);
  return MY_WAKE_UP_BY_TIMER;
}


void setup() {
  // put your setup code here, to run once:
  Serial.begin(250000);
  Serial.println("Start");

  // Configure RTC
  NRF_RTC0->TASKS_STOP = 1;
  NRF_RTC0->PRESCALER = 32;  
  NRF_RTC0->CC[0] = NRF_RTC0->COUNTER + (655);  //comparison for when to turn off the Rx.
  NRF_RTC0->EVTENSET = RTC_EVTENSET_COMPARE0_Msk;
  NRF_RTC0->INTENSET = RTC_INTENSET_COMPARE0_Msk;
  NRF_RTC0->TASKS_START = 1;
  NRF_RTC0->EVENTS_COMPARE[0] = 0;

  // Enable interrupt
  NVIC_SetPriority(RTC0_IRQn, 15);
  NVIC_ClearPendingIRQ(RTC0_IRQn);
  NVIC_EnableIRQ(RTC0_IRQn);
  Serial.println();
  Serial.println();
  Serial.println("Starting...");
}


void loop() {

  Serial.print(millis());
  Serial.print(" ");
  Serial.print(theCounter);
  Serial.print(" ");
  Serial.println(interrupt);
  myHwSleep(5000000);
}

/**
 * Reset events and read back on nRF52
 * http://infocenter.nordicsemi.com/pdf/nRF52_Series_Migration_v1.0.pdf
 */
#if __CORTEX_M == 0x04
#define NRF5_RESET_EVENT(event)                                                 \
        event = 0;                                                                   \
        (void)event
#else
#define NRF5_RESET_EVENT(event) event = 0
#endif

// This must be in one line
extern "C" { void RTC0_IRQHandler(void) {   theCounter=NRF_RTC0->COUNTER; NRF5_RESET_EVENT(NRF_RTC0->EVENTS_COMPARE[0]); interrupt++; NRF_RTC0->TASKS_CLEAR = 1; }}

and see if I can generate equivalent code which triggers on a pin change instead of an RTC event. If I can get that to work, then I'll take another stab at getting it to work based on the radio receiving a packet.

[NeverDie]

I was only partially done with the code, but I decided to run it anyway. Oddly enough, even though there is no reference to " RTC0_IRQHandler(void)" as being the event handler, it gets fired off anyway whenever I press the button (pin P0.16):

#include <nrf.h>
#include <MySensors.h>

int interrupt = 0;
uint32_t theCounter;


int8_t myHwSleep(unsigned long ms)
{
  hwSleepPrepare(ms);
   hwSleep();
  hwSleepEnd(ms);
  return MY_WAKE_UP_BY_TIMER;
}


void setup() {
  // put your setup code here, to run once:
  Serial.begin(250000);
  Serial.println("Start");

  //Configure GPIOTE 
  NRF_GPIOTE->CONFIG[0]=0x31001;  // Toggle Event; Pin P0.16; Event Mode 
                                  //So, any pin change on P0.16 will trigger an event.
                                   //On the Nordic nRF52 DK, Pin 0.16 is a button.
                                   
  NRF_GPIOTE->CONFIG[1]=0x131203;  //Initial setting: HIGH; Toggle Task; Pin P0.18; Task Mode
                                   //On the Nordic nRF52 DK, Pin 0.18 is an LED.
                                   //Note: initial setting of HIGH means that the LED will be initially OFF.

  NRF_GPIOTE->INTENSET=1;  //Enable an event on Pin P0.16 to trigger an interrupt.
                                   
  NRF_PPI->CH[0].EEP = (uint32_t)&NRF_GPIOTE->EVENTS_IN[0];  //P0.16 pin change occured.
  NRF_PPI->CH[0].TEP = (uint32_t)&NRF_GPIOTE->TASKS_OUT[1]; //Toggle LED on pin P0.18.
  
  NRF_PPI->CHENSET=B1; //enable Channel 0.

  // Enable interrupt
  NVIC_SetPriority(GPIOTE_IRQn, 15);
  NVIC_ClearPendingIRQ(GPIOTE_IRQn);
  NVIC_EnableIRQ(GPIOTE_IRQn);
  Serial.println();
  Serial.println();
  Serial.println("Starting...");
}


void loop() {

  Serial.print(millis());
  Serial.print(" ");
  Serial.print(theCounter);
  Serial.print(" ");
  Serial.println(interrupt);
  myHwSleep(5000000);
}

/**
 * Reset events and read back on nRF52
 * http://infocenter.nordicsemi.com/pdf/nRF52_Series_Migration_v1.0.pdf
 */
#if __CORTEX_M == 0x04
#define NRF5_RESET_EVENT(event)                                                 \
        event = 0;                                                                   \
        (void)event
#else
#define NRF5_RESET_EVENT(event) event = 0
#endif

// This must be in one line
extern "C" { void RTC0_IRQHandler(void) {   theCounter=NRF_RTC0->COUNTER; NRF5_RESET_EVENT(NRF_RTC0->EVENTS_COMPARE[0]); interrupt++; NRF_RTC0->TASKS_CLEAR = 1; }}

So, it looks as though, at present, there can be only a single ISR for an entire sketch?

[NeverDie]

Interesting result. I eliminated most of the sample code, and it actually manages to work even without an ISR! Instead of running an ISR, it appears to simply wake up from exactly where it last fell asleep. Then it continues running until it's put to sleep again:

#include <nrf.h>
#include <MySensors.h>

uint32_t buttonPressCounter=0;


int8_t myHwSleep(unsigned long ms)
{
  hwSleepPrepare(ms);
  hwSleep();
  hwSleepEnd(ms);
  return MY_WAKE_UP_BY_TIMER;
}


void setup() {
  // put your setup code here, to run once:
  Serial.begin(250000);
  Serial.println("Start");

  //Configure GPIOTE 
  NRF_GPIOTE->CONFIG[0]=0x31001;  // Toggle Event; Pin P0.16; Event Mode 
                                  //So, any pin change on P0.16 will trigger an event.
                                   //On the Nordic nRF52 DK, Pin 0.16 is a button.
                                   
  NRF_GPIOTE->CONFIG[1]=0x131203;  //Initial setting: HIGH; Toggle Task; Pin P0.18; Task Mode
                                   //On the Nordic nRF52 DK, Pin 0.18 is an LED.
                                   //Note: initial setting of HIGH means that the LED will be initially OFF.

  NRF_GPIOTE->INTENSET=1;  //Enable an event on Pin P0.16 to trigger an interrupt.
                                   
  NRF_PPI->CH[0].EEP = (uint32_t)&NRF_GPIOTE->EVENTS_IN[0];  //P0.16 pin change occured.
  NRF_PPI->CH[0].TEP = (uint32_t)&NRF_GPIOTE->TASKS_OUT[1]; //Toggle LED on pin P0.18.
  
  NRF_PPI->CHENSET=B1; //enable Channel 0.

  // Enable interrupt
  NVIC_SetPriority(GPIOTE_IRQn, 15);
  NVIC_ClearPendingIRQ(GPIOTE_IRQn);
  NVIC_EnableIRQ(GPIOTE_IRQn);
  Serial.println();
  Serial.println();
  Serial.println("Starting...");
}


void loop() {
  Serial.print("time=");
  Serial.print(millis());
  Serial.print(", buttonPressCounter=");
  Serial.println(buttonPressCounter++);
  myHwSleep(5000000);
}

[d00616]

@NeverDie said in nRF5 Bluetooth action!:

Question: Is
NRF5_RESET_EVENT(NRF_RADIO->EVENTS_PAYLOAD);

doing anything more than
NRF_RADIO->EVENTS_PAYLOAD=0;

is?

Yes. It reads back the register. http://infocenter.nordicsemi.com/topic/com.nordic.infocenter.nrf52/dita/nrf52/migration/functional.html?cp=2_4_0

[NeverDie]

Whenever I use:

#include <MySensors.h>

on the nRF52832, there is around a 10 second delay between the end of "void startup()" and the beginning of "loop()". Why is that, and what is the MySensors library doing during that interval?

[mfalkvidd]

@NeverDie it depends on the value of MY_TRANSPORT_WAIT_READY_MS
See https://github.com/mysensors/MySensors/issues/927 for a discussion on what happens when - we're trying to clarify the documentation.

[NeverDie]

@d00616 said in nRF5 Bluetooth action!:

P.S.: you can reduce the RX/TX time by enabling fast ramp up in MODECNF0 if you haven't to care about nRF51 compatibility.

Thanks for the tip. I tried it both ways. The first scope capture below is taken without MODECNF0 enabled on bit 0, and the second is with it enabled on bit 0.

I don't really see any difference. Do you?
Scale: 1mv=1ma. Scope captures of current drawn.

Maybe @jokgi can comment? His bio says he's a Senior Field Application Engineer at Nordic Semiconductor.
Maybe he sees (or knows) something that's not apparent about the fast ramp enable bit?

[d00616]

@NeverDie said in nRF5 Bluetooth action!:

Whenever I use:
#include <MySensors.h>

on the nRF52832, there is around a 10 second delay between the end of "void startup()" and the beginning of "loop()". Why is that, and what is the MySensors library doing during that interval?

As an alternative, you can define '#define MY_CORE_ONLY' and use ' transportInit(); transportSetAddress(MY_NODE_ID);' to initialize the radio. This dosn't work at the moment with the nRF5. I'm currently looking what the reason is. All radio registers are equal when it's initialized after MySensors normal and my setup(). It's not able to send or receive packages.

Maybe someone has an idea about the reason. Here is my code for nRF5 and other with nRF24.

// Undefine to work in gateway mode
#define MY_CORE_ONLY


#define MY_NODE_ID (0)

// Enable debug
#define MY_DEBUG
#define MY_DEBUG_VERBOSE_RF24
#define MY_DEBUG_VERBOSE_NRF5_ESB

// Enable and select radio type attached
#ifndef ARDUINO_ARCH_NRF5
#define MY_RADIO_NRF24
#else
#define MY_RADIO_NRF5_ESB
#include <nrf.h>
#endif
//#define MY_RADIO_RFM69
//#define MY_RADIO_RFM95

//#define MY_OTA_LOG_SENDER_FEATURE
//#define MY_OTA_LOG_RECEIVER_FEATURE

#ifndef MY_CORE_ONLY
#define MY_GATEWAY_SERIAL
#endif
#include <MySensors.h>

void state() {
#ifdef ARDUINO_ARCH_NRF5
 Serial.println("----------------------------------");
 Serial.print("NRF_RADIO->STATE  ");
 Serial.println(NRF_RADIO->STATE, HEX);
 Serial.print("NRF_RADIO->EVENTS_READY  ");
 Serial.println(NRF_RADIO->EVENTS_READY, HEX);
 Serial.print("NRF_RADIO->EVENTS_ADDRESS  ");
 Serial.println(NRF_RADIO->EVENTS_ADDRESS, HEX);
 Serial.print("NRF_RADIO->EVENTS_PAYLOAD  ");
 Serial.println(NRF_RADIO->EVENTS_PAYLOAD, HEX);
 Serial.print("NRF_RADIO->EVENTS_END  ");
 Serial.println(NRF_RADIO->EVENTS_END, HEX);
 Serial.print("NRF_RADIO->EVENTS_DISABLED  ");
 Serial.println(NRF_RADIO->EVENTS_DISABLED, HEX);
 Serial.print("NRF_RADIO->EVENTS_DEVMATCH  ");
 Serial.println(NRF_RADIO->EVENTS_DEVMATCH, HEX);
 Serial.print("NRF_RADIO->EVENTS_DEVMISS  ");
 Serial.println(NRF_RADIO->EVENTS_DEVMISS, HEX);
 Serial.print("NRF_RADIO->EVENTS_RSSIEND  ");
 Serial.println(NRF_RADIO->EVENTS_RSSIEND, HEX);
 Serial.print("NRF_RADIO->EVENTS_BCMATCH  ");
 Serial.println(NRF_RADIO->EVENTS_BCMATCH, HEX);
 Serial.print("NRF_RADIO->CRCSTATUS  ");
 Serial.println(NRF_RADIO->CRCSTATUS, HEX);
 Serial.print("NRF_RADIO->RXMATCH  ");
 Serial.println(NRF_RADIO->RXMATCH, HEX);
 Serial.print("NRF_RADIO->RXCRC  ");
 Serial.println(NRF_RADIO->RXCRC, HEX);
 Serial.print("NRF_RADIO->DAI  ");
 Serial.println(NRF_RADIO->DAI, HEX);
 Serial.print("NRF_RADIO->PACKETPTR  ");
 Serial.println(NRF_RADIO->PACKETPTR, HEX);
 Serial.print("NRF_RADIO->FREQUENCY  ");
 Serial.println(NRF_RADIO->FREQUENCY, HEX);
 Serial.print("NRF_RADIO->TXPOWER  ");
 Serial.println(NRF_RADIO->TXPOWER, HEX);
 Serial.print("NRF_RADIO->MODE  ");
 Serial.println(NRF_RADIO->MODE, HEX);
 Serial.print("NRF_RADIO->PCNF0  ");
 Serial.println(NRF_RADIO->PCNF0, HEX);
 Serial.print("NRF_RADIO->PCNF1  ");
 Serial.println(NRF_RADIO->PCNF1, HEX);
 Serial.print("NRF_RADIO->BASE0  ");
 Serial.println(NRF_RADIO->BASE0, HEX);
 Serial.print("NRF_RADIO->BASE1  ");
 Serial.println(NRF_RADIO->BASE1, HEX);
 Serial.print("NRF_RADIO->PREFIX0  ");
 Serial.println(NRF_RADIO->PREFIX0, HEX);
 Serial.print("NRF_RADIO->PREFIX1  ");
 Serial.println(NRF_RADIO->PREFIX1, HEX);
 Serial.print("NRF_RADIO->TXADDRESS  ");
 Serial.println(NRF_RADIO->TXADDRESS, HEX);
 Serial.print("NRF_RADIO->RXADDRESSES  ");
 Serial.println(NRF_RADIO->RXADDRESSES, HEX);
 Serial.print("NRF_RADIO->CRCCNF  ");
 Serial.println(NRF_RADIO->CRCCNF, HEX);
 Serial.print("NRF_RADIO->SHORTS  ");
 Serial.println(NRF_RADIO->SHORTS, HEX);
 Serial.print("NRF5_RADIO_TIMER->MODE ");
 Serial.println(NRF5_RADIO_TIMER->MODE);
 Serial.print("NRF5_RADIO_TIMER->BITMODE ");
 Serial.println(NRF5_RADIO_TIMER->BITMODE);
 Serial.print("NRF5_RADIO_TIMER->SHORTS ");
 Serial.println(NRF5_RADIO_TIMER->SHORTS);
 Serial.print("NRF5_RADIO_TIMER->PRESCALER ");
 Serial.println(NRF5_RADIO_TIMER->PRESCALER);
  // Reset compare events
#ifdef NRF51
  for (uint8_t i=0;i<4;i++) {
#else
  for (uint8_t i=0;i<6;i++) {
#endif
 Serial.print("NRF5_RADIO_TIMER->EVENTS_COMPARE[");
 Serial.print(i);
 Serial.print("] ");
 Serial.println(NRF5_RADIO_TIMER->EVENTS_COMPARE[i]);
}
Serial.println("----------------------------------");
#endif
}

void setup() {
  Serial.begin(115200);
  
  #ifdef MY_CORE_ONLY
  transportInit();
  delay(1000);
  transportSetAddress(MY_NODE_ID);
  #endif
}

void loop() {
  state();

  #ifdef MY_CORE_ONLY
  // Check for packages
  if (transportAvailable()) {
    uint8_t buffer[256];
    uint8_t num = transportReceive(&buffer);
    for (int i=0;i<num;i++) {
      if (buffer[i]<0x10) Serial.print("0");
      Serial.print(buffer[i], HEX);
      Serial.print(" ");
    }
    Serial.println();
  }
  #endif

  // Pause
  //sleep(1000); don't use this on SAMD. The device must be restored with reset doubleclick
  delay(1000);
  
  // Send data
  //transportSend(MY_NODE_ID, "abcd", 4, false);
}

@NeverDie said in nRF5 Bluetooth action!:

@d00616 said in nRF5 Bluetooth action!:

P.S.: you can reduce the RX/TX time by enabling fast ramp up in MODECNF0 if you haven't to care about nRF51 compatibility.

Thanks for the tip. I tried it both ways. The first scope capture below is taken without MODECNF0 enabled on bit 0, and the second is with it enabled on bit 0.

Have you checked the MODECNF0 register after ramp up? Maybe the register must be changed in a specific state?

[NeverDie]

Not sure why, but so far I haven't been able to get the radio to generate an interrupt (after it receives a packet) that directly wakes the MCU. So, as a workaround, I'm using PPI to have the radio toggle a GPIO output pin, which is directly shorted to a GPIO input pin. Changes in that input pin are able to trigger an interrupt which wakes the MCU. So, in this circuitous way, I'm able to get the radio to wake the MCU. It works, but with a propagation delay, and obviously I shouldn't have to be doing it so indirectly.

Has anyone else had any success yet in waking the MCU from sleep upon packet receipt by the radio?

Which interrupt register in the MCU is the interrupt generated by the radio tied to? Perhaps it needs to be premptively cleared. I think the next step is to check whether the radio's interrupt is even being received by the MCU.

[d00616]

@d00616 said in nRF5 Bluetooth action!:

Maybe someone has an idea about the reason. Here is my code for nRF5 and other with nRF24.

Now, I have the NRF5_ESB working under MY_CORE_ONLY condition. The HFCLK is not initialized. I do some code changes to allow using the radio in core only mode.

[NeverDie]

@d00616 said in nRF5 Bluetooth action!:

@d00616 said in nRF5 Bluetooth action!:

Maybe someone has an idea about the reason. Here is my code for nRF5 and other with nRF24.

Now, I have the NRF5_ESB working under MY_CORE_ONLY condition. The HFCLK is not initialized. I do some code changes to allow using the radio in core only mode.

I'm not sure what that means. Can you clarify what is working and what isn't, especially with regards to interrupts? If the code isn't yet ready, I'll just stick with the GPIO pins solution (above) and revisit this topic again at some future date when its further along.

[NeverDie]

Actually, there's another reason for wanting to avoid using the GPIO pins to intermediate waking up the MCU: earlier measurements in this thread showed that using the GPIO's in anything other than a "disconnected" state noticeably increases the current draw while sleeping.

[NeverDie]

@d00616 said in nRF5 Bluetooth action!:

The HFCLK is not initialized.

Not sure if it helps you at all, but to save extra energy I'm using the PPI to turn-on HFCLK before the Rx "listen-mode" begins, and then turn it off after the receiver is subsequently put to sleep:

  //Note: radio is assumed to be sleeping by this point, and with high frequency crystal oscillator turned off.
  NRF_PPI->CH[0].EEP = (uint32_t)&NRF_RTC0->EVENTS_OVRFLW;  //when COUNTER overflows.
  NRF_PPI->CH[0].TEP = (uint32_t)&NRF_CLOCK->TASKS_HFCLKSTART;  //turn-on the HF crystal oscillator

  NRF_PPI->CH[1].EEP = (uint32_t)&NRF_CLOCK->EVENTS_HFCLKSTARTED;  //After HF Clock started.
  NRF_PPI->CH[1].TEP = (uint32_t)&NRF_RADIO->TASKS_RXEN;  //turn on the radio receiver

  NRF_PPI->CH[2].EEP = (uint32_t)&NRF_RADIO->EVENTS_READY;  //After event READY, radio shall be in state RXIDLE.
  NRF_PPI->CH[2].TEP = (uint32_t)&NRF_RADIO->TASKS_START;  //Move from RXIDLE mode into RX mode.

  NRF_PPI->CH[3].EEP = (uint32_t)&NRF_RTC0->EVENTS_COMPARE[0];  // If time to turn off the radio receiver
  NRF_PPI->CH[3].TEP = (uint32_t)&NRF_RADIO->TASKS_STOP; //Move radio from RX mode back into RXIDLE mode
  
  NRF_PPI->CH[4].EEP = (uint32_t)&NRF_RTC0->EVENTS_COMPARE[1];  // If enough time has passed
  NRF_PPI->CH[4].TEP = (uint32_t)&NRF_RADIO->TASKS_DISABLE; //Sleep the radio
  NRF_PPI->FORK[4].TEP = (uint32_t)&NRF_CLOCK->TASKS_HFCLKSTOP; //Turn-off the high frequency crystal oscillator 
  
  NRF_PPI->CH[5].EEP = (uint32_t)&NRF_RTC0->EVENTS_COMPARE[2];  // If 100ms has passed
  NRF_PPI->CH[5].TEP = (uint32_t)&NRF_RTC0->TASKS_TRIGOVRFLW; //Set COUNTER so that it will overflow in 16 ticks.

  NRF_PPI->CH[6].EEP = (uint32_t)&NRF_RADIO->EVENTS_END;  //packet received.
  NRF_PPI->CH[6].TEP = (uint32_t)&NRF_GPIOTE->TASKS_OUT[1]; //Make pin P0.18. be LOW (turn on the LED).

  NRF_PPI->CH[7].EEP = (uint32_t)&NRF_GPIOTE->EVENTS_IN[0];  //P0.16 pin change occured.
  NRF_PPI->CH[7].TEP = (uint32_t)&NRF_GPIOTE->TASKS_OUT[2]; //Make pin P0.17. be LOW (turn on the LED).
  
  NRF_PPI->CHENSET=B11111111; //enable Channels 7,6,5,4,3,2,1,and 0.

It works. :)

[NeverDie]

@d00616

Can you see any reason as to why the radio isn't waking the MCU after it receives a packet? Here's the entire sketch:

#include <nrf.h>
//#include <MySensors.h>
#include <RH_NRF51.h>

// Singleton instance of the radio driver
RH_NRF51 nrf51;

bool toggle=true;
uint32_t packetCounter=0;
uint8_t myBuffer[20];  //required buffer for transmitting packet
uint8_t my_default_network_address[] = {0xE7, 0xE7, 0xE7, 0xE7, 0xE7};

bool mySetNetworkAddress(uint8_t* address, uint8_t len)
{
    if (len < 3 || len > 5)
  return false;

    // First byte is the prefix, remainder are base
    NRF_RADIO->PREFIX0    = ((address[0] << RADIO_PREFIX0_AP0_Pos) & RADIO_PREFIX0_AP0_Msk);
    uint32_t base;
    memcpy(&base, address+1, len-1);
    NRF_RADIO->BASE0 = base;

    NRF_RADIO->PCNF1 =  (
  (((sizeof(myBuffer)) << RADIO_PCNF1_MAXLEN_Pos)  & RADIO_PCNF1_MAXLEN_Msk)  // maximum length of payload
  | (((0UL)        << RADIO_PCNF1_STATLEN_Pos) & RADIO_PCNF1_STATLEN_Msk) // expand the payload with 0 bytes
  | (((len-1)      << RADIO_PCNF1_BALEN_Pos)   & RADIO_PCNF1_BALEN_Msk)); // base address length in number of bytes.

    return true;
}

void myHwSleepPrepare(unsigned long ms)
{
  // Idle serial device
  NRF_UART0->TASKS_STOPRX = 1;
  NRF_UART0->TASKS_STOPTX = 1;
  NRF_UART0->TASKS_SUSPEND = 1;

  //NRF_CLOCK->TASKS_HFCLKSTOP = 1;
  
  // Enable low power sleep mode
  NRF_POWER->TASKS_LOWPWR = 1;
}

// Sleep in System ON mode
inline void doTheSleep()
{
  __WFE();
  __SEV();
  __WFE();
}

void myHwSleepEnd(unsigned long ms)
{
  // Start HFCLK
  //if (nrf5_pwr_hfclk) {
  if (false) {
    NRF_CLOCK->EVENTS_HFCLKSTARTED = 0;
    NRF_CLOCK->TASKS_HFCLKSTART = 1;
    while (NRF_CLOCK->EVENTS_HFCLKSTARTED == 0)
      ;
    // Enable low latency sleep mode
    NRF_POWER->TASKS_CONSTLAT = 1;
  }

   // Start serial device
//#ifndef MY_DISABLED_SERIAL
  NRF_UART0->TASKS_STARTRX = 1;
  NRF_UART0->TASKS_STARTTX = 1;
//#endif
}

void myHwSleep(unsigned long ms)
{
  myHwSleepPrepare(ms);
  doTheSleep();
  //now sleeping
  myHwSleepEnd(ms);

}



void setup() {
  Serial.begin(250000);
  Serial.println();
  Serial.println("Starting...");
  Serial.flush();

  NRF_POWER->DCDCEN=1;  //enable the DCDC voltage regulator as the default.
  
  // Configure RTC
  NRF_RTC0->TASKS_STOP = 1;  //stop the RTC counter so that it can be configured without incident

  // Enable interrupt
  //NVIC_SetPriority(GPIOTE_IRQn, 15);
  //NVIC_ClearPendingIRQ(GPIOTE_IRQn);
  //NVIC_EnableIRQ(GPIOTE_IRQn);
  
  NVIC_SetPriority(RADIO_IRQn, 15);
  NVIC_ClearPendingIRQ(RADIO_IRQn);
  NVIC_EnableIRQ(RADIO_IRQn);
  NRF_RADIO->INTENSET = B1000;  //interrupt MCU if a packet is received.
  while (NRF_RADIO->INTENSET != B1000) {}  //wait until confirmed
      
  //NRF_GPIOTE->INTENSET = 1;  //interrupt MCU if change detected on pin P0.16.
  //while (NRF_GPIOTE->INTENSET != 1) {}  //wait until confirmed
  
  Serial.print("LFCLKSTAT=0X");
  Serial.print(NRF_CLOCK->LFCLKSTAT,HEX);
  Serial.print("=B");
  Serial.println(NRF_CLOCK->LFCLKSTAT,BIN);
  Serial.flush();

  NRF_RADIO->FREQUENCY=123;
  NRF_RADIO->MODE=1;  //set 2Mbps datarate.
  NRF_RADIO->MODECNF0=1;  //enable fast ramp-up of radio from DISABLED state.

  if (!nrf51.init())
    Serial.println("init failed");
  mySetNetworkAddress(my_default_network_address, sizeof(my_default_network_address));   
  
  if ((NRF_CLOCK->LFCLKSTAT)>>2) {//if LF clock is running
    NRF_CLOCK->TASKS_LFCLKSTOP=1;  //stop the clock
    while ((NRF_CLOCK->LFCLKSTAT)& 1)  {}  //busy-wait until LF clock has stopped running
    Serial.println("LF clock is stopped.");
  }

  Serial.print("LFCLKSTAT=0x");
  Serial.print(NRF_CLOCK->LFCLKSTAT,HEX);
  Serial.print("=B");
  Serial.println(NRF_CLOCK->LFCLKSTAT,BIN);
  Serial.flush();
  
  NRF_CLOCK->LFCLKSRC=1;  //use the crystal oscillator.
  while (!(NRF_CLOCK->LFCLKSRC=1)) {}  //

  Serial.println("Crystal oscillator is now the LF choice.");
  Serial.print("LFCLKSTAT=0x");
  Serial.print(NRF_CLOCK->LFCLKSTAT,HEX);
  Serial.print("=B");
  Serial.println(NRF_CLOCK->LFCLKSTAT,BIN);
  Serial.flush();
 
  NRF_CLOCK->TASKS_LFCLKSTART=1;  //start the crystal oscillator clock


  
  while (!(NRF_CLOCK->EVENTS_LFCLKSTARTED)) {}  //busy-wait until the clock is confirmed started.
  Serial.println("Low Frequency crystal oscillator started.");
  Serial.flush();


  Serial.print("LFCLKSTAT=0x");
  Serial.print(NRF_CLOCK->LFCLKSTAT,HEX);
  Serial.print("=B");
  Serial.println(NRF_CLOCK->LFCLKSTAT,BIN);
  
  Serial.print("LFCLKSRC=0x");
  Serial.print(NRF_CLOCK->LFCLKSRC,HEX);
  Serial.print("=B");
  Serial.println(NRF_CLOCK->LFCLKSRC,BIN);
  
  Serial.print("Present PRESCALER=");
  Serial.println(NRF_RTC0->PRESCALER);

  Serial.print("LFCLKSTAT=0x");
  Serial.print(NRF_CLOCK->LFCLKSTAT,HEX);
  Serial.print("=B");
  Serial.println(NRF_CLOCK->LFCLKSTAT,BIN);
  NRF_RTC0->PRESCALER=0;  //32768 frequency
  while (NRF_RTC0->PRESCALER!=0)  {}  //busy-wait until pre-scaler changes
  Serial.print("New PRESCALER=");
  Serial.println(NRF_RTC0->PRESCALER);

  Serial.println();
  Serial.println("Finished setup.");
  Serial.flush();

  //Radio enters RXIDLE soon after COUNTER overflows.
  NRF_RTC0->CC[0] = 24;  //the time to exit RX state.
  NRF_RTC0->CC[1] = 25;  //the time to put radio to sleep from RXIDLE
  NRF_RTC0->CC[2] = 3300;  //the time to restart the cycle

  NRF_RTC0->EVENTS_COMPARE[0] = 0;  //Clear the event flag.
  NRF_RTC0->EVENTS_COMPARE[1] = 0;  //Clear the event flag.
  NRF_RTC0->EVENTS_COMPARE[2] = 0;  //Clear the event flag.
    
  NRF_RADIO->TASKS_DISABLE=1;  //sleep the radio
  while (NRF_RADIO->STATE) {}; //wait until radio is DISABLED (i.e. STATE=0);

  //Configure GPIOTE 
  NRF_GPIOTE->CONFIG[0]=0x31001;  // Toggle Event; Pin P0.16; Event Mode 
                                  //So, any pin change on P0.16 will trigger an event.
                                   //On the Nordic nRF52 DK, Pin 0.16 is a button.
                                   
  NRF_GPIOTE->CONFIG[1]=0x131203;  //Initial setting: HIGH; Toggle Task; Pin P0.18; Task Mode
                                   //On the Nordic nRF52 DK, Pin 0.18 is an LED.
                                   //Note: initial setting of HIGH means that the LED will be initially OFF.

  NRF_GPIOTE->CONFIG[2]=0x131103;  //Initial setting: HIGH; Toggle Task; Pin P0.17; Task Mode
                                   //On the Nordic nRF52 DK, Pin P0.17 is an LED.
                                   //Note: initial setting of HIGH means that the LED will be initially OFF.          

  
  //Note: radio is assumed to be sleeping by this point, and with high frequency crystal oscillator turned off.
  NRF_PPI->CH[0].EEP = (uint32_t)&NRF_RTC0->EVENTS_OVRFLW;  //when COUNTER overflows.
  NRF_PPI->CH[0].TEP = (uint32_t)&NRF_CLOCK->TASKS_HFCLKSTART;  //turn on the HF crystal oscillator

  NRF_PPI->CH[1].EEP = (uint32_t)&NRF_CLOCK->EVENTS_HFCLKSTARTED;  //After HF Clock started.
  NRF_PPI->CH[1].TEP = (uint32_t)&NRF_RADIO->TASKS_RXEN;  //turn on the radio receiver
  //NRF_PPI->FORK[1].TEP = (uint32_t)&NRF_GPIOTE->TASKS_OUT[0]; //Make pin P0.18. be HIGH


  NRF_PPI->CH[2].EEP = (uint32_t)&NRF_RADIO->EVENTS_READY;  //After event READY, radio shall be in state RXIDLE.
  NRF_PPI->CH[2].TEP = (uint32_t)&NRF_RADIO->TASKS_START;  //Move from RXIDLE mode into RX mode.

  NRF_PPI->CH[3].EEP = (uint32_t)&NRF_RTC0->EVENTS_COMPARE[0];  // If time to turn off the radio receiver
  NRF_PPI->CH[3].TEP = (uint32_t)&NRF_RADIO->TASKS_STOP; //Move radio from RX mode back into RXIDLE mode
  
  NRF_PPI->CH[4].EEP = (uint32_t)&NRF_RTC0->EVENTS_COMPARE[1];  // If enough time has passed
  NRF_PPI->CH[4].TEP = (uint32_t)&NRF_RADIO->TASKS_DISABLE; //Sleep the radio
  NRF_PPI->FORK[4].TEP = (uint32_t)&NRF_CLOCK->TASKS_HFCLKSTOP; //Turn off the high frequency crystal oscillator 
  
  NRF_PPI->CH[5].EEP = (uint32_t)&NRF_RTC0->EVENTS_COMPARE[2];  // If 100ms has passed
  NRF_PPI->CH[5].TEP = (uint32_t)&NRF_RTC0->TASKS_TRIGOVRFLW; //Set COUNTER so that it will overflow in 16 ticks.

  NRF_PPI->CH[6].EEP = (uint32_t)&NRF_RADIO->EVENTS_END;  //packet received.
  NRF_PPI->CH[6].TEP = (uint32_t)&NRF_GPIOTE->TASKS_OUT[1]; //Make pin P0.18. be LOW (turn on the LED).

  NRF_PPI->CH[7].EEP = (uint32_t)&NRF_GPIOTE->EVENTS_IN[0];  //P0.16 pin change occured.
  NRF_PPI->CH[7].TEP = (uint32_t)&NRF_GPIOTE->TASKS_OUT[2]; //Make pin P0.17. be LOW (turn on the LED).
  
  NRF_PPI->CHENSET=B11111111; //enable Channels 7,6,5,4,3,2,1,and 0.
  
  NRF_CLOCK->TASKS_LFCLKSTART=1;  //start the crystal oscillator clock
  
  while (!(NRF_CLOCK->EVENTS_LFCLKSTARTED)) {}  //busy-wait until the clock is confirmed started.
  Serial.println("Crystal oscillator started.");
  Serial.flush();

  NRF_RTC0->EVTENSET=0x70003;  //enable routing of RTC TICK, OVRFLW, and comparison events to PPI for the comparisons
  while (NRF_RTC0->EVTEN!= (0x70003)) {};  //wait until EVTENSET setting is confirmed.
  
  NRF_RTC0->EVENTS_TICK=0;  //clear TICKS flag
  NRF_RTC0->EVENTS_OVRFLW=0;  //clear overflow flag
  NRF_RADIO->EVENTS_END=0;  //clear payload received flag.

  NRF_CLOCK->TASKS_HFCLKSTOP=1;  //Turn off the high frequency crystal oscillator.
  NRF_RTC0->TASKS_TRIGOVRFLW=1;  //prepare COUNTER so that an overflow will ensue in 16 ticks.
  while (NRF_RTC0->COUNTER!=0xFFFFF0) {} //wait until COUNTER is primed to overflow.
  NRF_RTC0->TASKS_START=1;  //  Resume the RTC, which had been paused.
  while ((NRF_RTC0->EVENTS_TICK==0)) {}  //wait until the radio is confirmed to be started.
}
uint32_t loopCounter=0;
void loop() {

  
  Serial.print("time=");
  Serial.print(millis());
  Serial.print(", packetCounter=");
  Serial.println(packetCounter);
  
  Serial.flush();
  
  myHwSleep(500000000);  //sleep 100ms.  Already offset in setup by 1ms from wake-up of PPI.
}


// * Reset events and read back on nRF52
//* http://infocenter.nordicsemi.com/pdf/nRF52_Series_Migration_v1.0.pdf
 
#if __CORTEX_M == 0x04
#define NRF5_RESET_EVENT(event)                                                 \
        event = 0;                                                                   \
        (void)event
#else
#define NRF5_RESET_EVENT(event) event = 0
#endif


// This must be in one line
extern "C" { void RADIO_IRQHandler(void) {packetCounter++; NRF5_RESET_EVENT(NRF_RADIO->EVENTS_END); NRF_RADIO->EVENTS_END=0; }}

The PPI does toggle an LED each time it receives a packet, but unfortunately the CPU remains asleep. Nonetheless, it does seem to follow your prescription for the ISR.

[Uhrheber]

@NeverDie
What if you activate a pin change interrupt/wake at the pin the PPI toggles?
Or connect it to another pin with pin change wake?

[NeverDie]

@Uhrheber said in nRF5 Bluetooth action!:

@NeverDie
What if you activate a pin change interrupt/wake at the pin the PPI toggles?
Or connect it to another pin with pin change wake?

Yes, I have tested that as a workaround. It "works", but using GPIO pins increases the current drain.

[NeverDie]

Well, I guess it's almost moot now, because I found and tested a better workaround. I re-wrote the PPI code so that after packet receipt, the PPI triggers an RTC0 overflow. It is that which is then used to wake-up the MCU. No GPIO pins need be involved, so no propagation delays and no increase in current drawn. It works.

I still think the radio ISR code (above) should have worked, but fortunately that's no longer holding me back now that I have a good enough workaround. :)

[NeverDie]

However, there's one fly in the ointment remaining. It turns out that some other timer is sometimes waking up the CPU:

time=15798, Radio STATE=0, COUNTER=0x49, packetCounter=22
time=15900, Radio STATE=0, COUNTER=0x49, packetCounter=23
time=16001, Radio STATE=0, COUNTER=0x49, packetCounter=24
time=16103, Radio STATE=0, COUNTER=0x49, packetCounter=25
time=16204, Radio STATE=0, COUNTER=0x49, packetCounter=26
time=16306, Radio STATE=0, COUNTER=0x49, packetCounter=27
time=512000, Radio STATE=0, COUNTER=0x2035, packetCounter=27
time=1024000, Radio STATE=0, COUNTER=0x269, packetCounter=27
time=1536000, Radio STATE=0, COUNTER=0x1803, packetCounter=27
time=2048000, Radio STATE=3, COUNTER=0x36, packetCounter=27
time=2560000, Radio STATE=0, COUNTER=0x1570, packetCounter=27
time=3072000, Radio STATE=0, COUNTER=0x3104, packetCounter=27
time=3584000, Radio STATE=0, COUNTER=0x1337, packetCounter=27
time=4096000, Radio STATE=0, COUNTER=0x2871, packetCounter=27
time=4608000, Radio STATE=0, COUNTER=0x1104, packetCounter=27
time=5120000, Radio STATE=0, COUNTER=0x2638, packetCounter=27

All the lines labelled packetCounter=27 (after the first one that is) are a result of this. Looking at the time, they appear to happen on the rollover of some other timer (?)--apparently the one that is responsible for keeping track of millis(). I can filter them out after-the-fact, but I'd rather they not be waking up the CPU for no reason, as that is just a waste of energy.