Best posts made by reinhold

reinhold

Finally got the PCBs from AllPCB.com (cost 5 Euros and took a total of 7 days from order submission to free DHL delivery to Europe!!!) for my own MySensors Arduino Pro Mini prototyping board. Unfortunately the soldering iron broke during my assembly, so it's not fully finished and I couldn't test it yet, either...
Arduino Pro Mini IO shield

This board is inspired by the Nano IO shields that are offered on AliExpress and improves it further for my needs (and switched to the Pro Mini instead of the Nano).

Each analog and digital pin of the Pro Mini has its own VCC and GND pins,
the board also provides its own voltage regulator, solder pins for by NRF24L01+ and RFM69H are provided (plus the 5V->3.3V XC6206 regulator),
either a tiny 55-pin breadboard or three I²C connectors can be placed on the board.
One can also use PogoPins instead of soldering the Pro Mini (or headers for it) to burn the bootloader or change fuses on the Pro Mini via the ICSP connector.

All design files are available on GitHub: https://www.openhardware.io/view/538/Arduino-Pro-Mini-IO-Shield

reinhold

Today I finished the coding for my prototype of a laser distance sensor (intended to measure the water level for my automatic in-door flower watering pump). The sensor is connected via I²C and has sleep pin.

The most work was implementing support for the VL52L0X laser distance sensor and for my 128x64 OLED display to NodeManager (PRs submitted as https://github.com/mysensors/NodeManager/pull/244 and https://github.com/mysensors/NodeManager/pull/245).

The OLED is really useful when prototyping sensor nodes. Out of the box, my NodeManager OLED implemention will display the values of all attached sensors without any coding. Simply create the DisplaySSD1306 after all other sensors, and the OLED will pick up and display all sensors automatically...

Once everything works, of course the OLED is not desired for the water level sensor running on batteries...

reinhold

Yes, 1.27mm pitch should be possible with pogo pins (I have never done them myself, though).

You need to buy the smaller pogo pins (diameter 0.68mm). Some examples by other hackaers can be found e.g. at

reinhold

@gohan I'm using the SSD1306Ascii library, which does not use a display buffer and does not support graphics, only text. The drawback is that to prevent screen flickering, you have to manually clean each line of text to the EOL. Otherwise letters that are not overwritten by new text will not be cleared. See my PR for NodeManager how it works. With my approach, there is absolutely no screen flicker, the display updates properly and the memory requirements are minimal (the library docs say its 53 bytes)

reinhold

(I know this post is off-topic regarding the original request... Sorry for that)

If your concern is mainly about connecting the radio to the arduino, then I can warmly recommend one of those "Arduino nano IO shields":
https://www.aliexpress.com/item/For-arduino-Nano-Terminal-Expansion-Board-Adapter-IO-Shield-Electronic-Circuit-328P-w-XBEE-nRF24L01-Socket/32841357885.html

You just plug in the nrf24l01 (I'm using a small adapter PCB to use the SMD version with the pin header) and the nano and you are ready to go. Also comes with a connector for a 9V power adapter (which I needed for the gas sensors drawing 100+ mA). It also has the four pins for I2c (VCC, GND, SCL, SDA) and Serial (GND, VCC, Tx, Rx) next to each other, and it provides +5V and GND together with each in-/output pin.

To make prototyping even easier, I unsoldered (or broke off) the small female pin headers for the xbee and used two-sided duct tape to add a tiny breadboard instead (where I simply plugin in I2C devices like an OLED or a sensor):
https://www.aliexpress.com/item/7pcs-Mini-55-Points-Breadboard-Solderless-Prototype-Tie-point/32661906252.html

reinhold

Another idea might be to connect all analog sensors to I2C Analog-digital converters like the ADS1115:
https://www.aliexpress.com/store/product/I2C-ADS1115-16-Bit-ADC-4-channel-Module-with-Programmable-Gain-Amplifier-2-0V-to-5/324775_32903062908.html

As you can hook up multiple devices to the same i2c bus, simply attach the OLED and two of those ADS1115 boards (apparently you can assign up to 7 different I2C addresses to the ADC boards...) to the I2C bus.

reinhold

After some more googling, I think I found the cause of the issue: I bought some cheap SMD version of the nrf24l01 on aliexpress.
Apparently, that SMD version with the epoxy blob is a cheap knock-off that does not really include a genuine nrf24l01 chip, but only a similar chip. While the board is pin-compatible and API-compatible to the nrf24l01, the over-the-air data frame format is apparently NOT compatible with the real NRF24L01+ chip:

So, no wonder my smd gateway is not communicating (or rather unable to understand the communication) with the nodes that use real nrf24l01+ modules.... Guess I'll have to wait for the real, non-blob nrf24l01 SMD modules, which I also ordered a while ago and which should arrive any day now....

reinhold

If you insist on connecting the analog sensors to the arduino and switch to a software I2C implementation on non-hardware I2C pins, you might simply extend the SSD1306Ascii library. It currently has classes for the SSD1306 over the AVR hardware i2c, another class for generic Wire implementations (not tailored to atmel chips; e.g. I'm using it on nrf51822), and the SPI devices.

Looking at the SoftwareI2CLibrary docs, it appears that they even provide a Wire interface (SoftWire.h), so you might even get away with the SSD1306AsciiWire class for the OLED.

If that does not work, you'll have to write your own software I2C implementation for the SSD1306Ascii class (e.g. takt SSD1306AsciiWire, rename it to SSD1306AsciiSoftI2C and adjust it to use the SoftwareI2C library for all I2C communication).)

reinhold

@user2684 Thanks a lot for the architecture change, which makes a lot of sense conceptually.

Unfortunately, it appears to use more memory than before. I'm working on an air quality board with eight MQ sensors, an MH-Z19 CO2 sensor and a Plantower PMSA003 particulate matter sensor. In previous development versions (1.7-dev, before today), the eight MQ sensors and the MH-Z19 worked fine, but now after your big merge of #229 the sketch appears to run out of memory after adding the child of the sixth MQ sensor. Do you see any chance to optimize for memory?

Old sketch (using a previous development version of NodeManager, without the PMSA003; 155 bytes left after all nine sensors are fully initialized): https://github.com/open-tools/NodeManager_GasSensor/tree/master/NodeManager_GasSensor

New sketch (using the latest version of NodeManager, plus a PMSA003): https://github.com/kainhofer/NodeManager/tree/GasSensor
That sketch runs out of memory with the sixth MQ sensor (I added debug output with free memory at a lot of spots). Of course, I have commented out the PMSA003 completely to have a correct comparison.

FWIW, the sketch is for this board: https://github.com/open-tools/NodeManager_GasSensor/blob/master/images/IMAG2267.jpg

reinhold

@nca78 Thanks for the suggestion to use the blue pill STM32 boards. I haven't thought of it (I only looked at the ESP8266, but that has only one ADC). I have a few lying around here, but never got around to trying them, as I first need to burn the bootloader. It looks quite promising, but the boards are huge, so I'll need to enlarge my PCB...
The need for a 5V->3.3V regulator is no issue, as the NRF24 already needs 3.3V. The 5V analog level of the MQ sensors will need some converter (the analog ADC inputs are marked as non-5V-tolerant...), but then in turn I can get rid of the voltage dividers for the PMSA003. The larger issue seems to be the connection of the nrf24, which takes away 4 ADC pins, so there are only 6 ADC pins left, while I have 8 analog sensors

Still, for now I have the PCBs with the ProMini, so I'll try to strip down the Sensor or SensorMQ classes for my own use.