My own board (50mm x 30mm)

[mfalkvidd]

The processor is guaranteed to work within the specified limits. Outside the specified limits, no guarantees are made. It might work, it might not work or it might work slightly with strange glitches.

[rmtucker]

I see now.Thank you
Has anyone modified Gertsanders Firmware to run at 1Mhz?
That would give reasonably stable results down to 1.8v.
I don't have the skills to compile from scratch and cater for the led on pin8 etc.

[GertSanders]

@rmtucker The firmware itself does not need to be changed to use the internal oscillator. You accomplish that by using a different set of fuse values:
atmega328pO4M8i.bootloader.low_fuses=0xE2
atmega328pO4M8i.bootloader.high_fuses=0xDE
atmega328pO4M8i.bootloader.extended_fuses=0x07

This sets the processor to a mode using the internal oscillator.

Add the call to divide the frequency by 8 (can be done in the sketch itself) and you have a 1MHz internal clock.

[rmtucker]

@GertSanders So have you never found it a problem running at 8Mhz?
Do most of your sensors work ok below the 2.4v threshold?
Guess i will find out when the pcb boards arrive:smiley:

[GertSanders]

@rmtucker Short answer: yes. So far most my sensors are working fine and all sit above 2.4V but I have not had problems when they do below 2.4V

There is one sensor now that has a battery in decline. This sensor uses a lot of power and goes through it's batteries very fast. So it is a good test for this low voltage work. It is now at 2.11V and still sends messages every 5 minutes. On the first graph you can see it is still working fine wel below 2.4V and it is clocked at 8MHz with a crystal.

I have a notification on all my sensors so that when the battery voltage goes below 2V I get a Prowl from Domoticz. This has only happened on this sensor (twice so far), because I was using NiMH batteries (which discharge faster than alkaline). Around 2 november I put in 2 alkaline batteries (AAA), but these were not brand new.

Most of my sensors have a discharge pattern as here below:

[rmtucker]

@GertSanders What rate is the sensor in the very bottom graph sending messages?
That discharge rate looks very nice.

@GertSanders said:

@rmtucker The firmware itself does not need to be changed to use the internal oscillator. You accomplish that by using a different set of fuse values:
atmega328pO4M8i.bootloader.low_fuses=0xE2
atmega328pO4M8i.bootloader.high_fuses=0xDE
atmega328pO4M8i.bootloader.extended_fuses=0x07

This sets the processor to a mode using the internal oscillator.

Add the call to divide the frequency by 8 (can be done in the sketch itself) and you have a 1MHz internal clock.

Problem with using div/8 in the sketch and not altering the bootloader is that all the timings are off for baud rates and pwm etc.
Where if it is altered in the bootloader it all works as it should.

Last question i promise :yum:

I currently use the arduino mini pro and when uploading sketches to it using ftdi,i have to press the reset button to get the upload to work.
Will i have the same problem with your boards?

[GertSanders]

@rmtucker On my board I do not need to press a reset to be able to upload sketches, since I connected the RESET pin to the FTDI header via a capacitor.

So if the FTDI interface does the reset via RTS pin, then it will reset the board and you can upload sketches.

The sensor in the last graph sends it's voltage and temperature every 5 minutes, even if the value is sometimes the same as the previous one. It also sends it's battery voltage every 5 minutes.

In my last version of the sketch I have now added a change based on the Sensebender sketch. That sketch sends it's temperature or humidity only if the change is a minimal difference with the previously sent temperature or humidity. It always sends it's battery level every half hour. That should make it last minimum a year on 2 AAA batteries.

Below is a graph of another sensor sending data every 5 minutes.

[rmtucker]

In comparison here is an ESP8266 doing the same job every 5mins
But that is 4 AA Alkaline batteries.
And by the look of todays voltage it is on it's way out.

[Zeph]

@GertSanders said:

It seems you have removed the crystal and capacitors and plan to use the internal oscillator, I did this as well. Works most of the time, but uploading of sketches can give transmission errors of you go above 57K6 baud. Better to transmit at 36Kbit then (needs a change in the BOARDS.TXT file of Arduino IDE)

76K8 baud works better than 57K6 (division from 8 MHz has less error), and there are Optiboot variants which support it (with theBOARDS.TXT change you mention). Or 38K4 baud (half that) as you suggest, which is no more timing accurate than 76K8 but by being slower still may give more margin for sloppy edges or the like - if needed.

[Carl H]

Hi GertSanders,

After ordered and make 3 of 50mm x 30mm board with success. Now I ordered the AC Capable 50mm x 50mm board. I try to read the schema and I have some question. If I want to use this board with only 2 AAA battery, Do I need to use AMS1117? and witch jumper do I need to close? It is optional to use AT24C ?

Thank you for your help

[GertSanders]

@Carl-H To use the board with AA batteries you do NOT need to place the AMS1117. But you will need to short the jumper "BAT" which you will find on the same surface as the AMS1117 if you want to feed the NRF24 with the same power.
The batteries are connected to the Vcc power line. The NRF24 is connected to the 3V3 power line. There is no interconnection, unless you use the AMS1117 or you short the jumper "BAT".

The AT24C's are optional. If you do plan to use them, you will also need to place the I2C pull resistors and you will need to short the jumpers RSCL and RSDA. These two jumpers connect the pull-up resistors to the SCL and SDA lines.
If you use a sensor connected to the pins SCL/SDA of the extension connector you sometimes have no need for pull-ups as the sensor itself has them.
The jumpers SCL-SDA and SDA-SCL are there to allow switching the signals of the SCL/SDA pins on the extension connector. The jumper closest to the board edge is for the pin on the very edge of the connector, the jumper close to the ATSHA is for the second pin. Without shorting these two jumpers, the pins on the extension connector have no function.
Some sensor-boards have a SDA-SCL-GND-3V3 connector, others have a SCL-SDA-GND-3V3 pattern. The jumpers are there to be able to use both types.

[Carl H]

Thanks for your clear explication! I have another question, where is the FTDI port ?

[GertSanders]

@Carl-H It is part of the expansion connector.

I added more info on the OpenHardware.io site.

[rmtucker]

Ok my boards arrived from DirtyPCB.
A couple of questions:-

1.I am not using NR2 (The radio socket that protrudes),Also i am using the internal osc and not the xtal.

So can i leave out C9,NR2 Socket,C5,C6,Xtal ?

2.What are C2,C3 doing.
The socket for the cpu i have fitted will not let me squeeze them in.

Should i solder them in underneath or can they be left out?

[BartE]

@mtucker

1. Yes you are right about leaving out these components, but if you use NR1 i should leave out C8 and keep C9 (mount the decouple C's as close to the decouple component as possible)

2. these components are for decoupling the uP. You can mount them at the bottom, do not leave the out.
   I used a tip from earlier in this forum thread for gaining a little bit more space when using these

Cheerz

[GertSanders]

@BartE answered perfectly. You can leave out C5,C6 and XTAL if you use the internal oscillator. C9 is for the NRF24, no matter if you use NR1 or nR2 socket. And yes, you only need 1 socket, so if you use NR1, no need to add NR2 (and vice versa).
Socket NR2 is for the longer (and power amplified) radio with external antenna, NR1 was intended for the standard NRF24L01+ with PCB antenna.
C2 decouples AVCC (the analog power input), just as C1 decouples the VCC (digital) power input. C3 stabilises the analog reference input. If you do not use the analog->digital conversion, you could skip C3 as well.

I also do not use standard 28 pin sockets, but strip sockets just like BartE.
In the image here I used a standard socket, but cut away the middle "bridge" to allow mounting the decoupling capacitors.

https://www.openhardware.io/uploads/568faa0cbaba42246aa57103/image/IMG_7527.jpg

In the image below I use the strips BartE mentioned:

https://www.openhardware.io/uploads/568faa0cbaba42246aa57103/image/IMG_7686.jpg

More images and details are here:

https://www.openhardware.io/view/5/Battery-based-atmega328p-sensor-no-SMD

[rmtucker]

I am pulling out what hair i have left.
All i am getting is this:-
find parent
send: 253-253-255-255 s=255,c=3,t=7,pt=0,l=0,sg=0,st=bc:
find parent
send: 253-253-255-255 s=255,c=3,t=7,pt=0,l=0,sg=0,st=bc:
find parent
send: 253-253-255-255 s=255,c=3,t=7,pt=0,l=0,sg=0,st=bc:
find parent
send: 253-253-255-255 s=255,c=3,t=7,pt=0,l=0,sg=0,st=bc:
find parent
send: 253-253-255-255 s=255,c=3,t=7,pt=0,l=0,sg=0,st=bc:
find parent
send: 253-253-255-255 s=255,c=3,t=7,pt=0,l=0,sg=0,st=bc:
Init complete, id=253, parent=255, distance=255
Battery:3.161 Batt%:90 Temperature:21.73C Humidity:56%
find parent
send: 253-253-255-255 s=255,c=3,t=7,pt=0,l=0,sg=0,st=bc:

[sundberg84]

Node 253 tries to connect and fint its way to the gateway (find parent) but doesnt get any respons.
Do you have a working gateway - what does the gateway log looks like?

[rmtucker]

Yes the gateway has been working fine.
I will connect the gateway back up to the computer and see what it is saying and let you know.

[GertSanders]

Which controller are you using?