💬 AC/DC/Batteries capable atmega328p board

  • Hardware Contributor

    Added a sketch to show how to use this board as a node with SMS capability (a SMS gateway for a Mysensors network if you will).

  • @GertSanders Can you give me a hint? I have 10 of this board and for one I want to use with external DC 5v. For this one, I put the AMS1117. All is working when I check with my meter, I have 3.3v for the NRF24 and 5v for the ATMEGA328P. Now when I use this board with DHT22 temp sensor (plug into D7), I check my scketch with FTDI cable and the Serial Monitor of Arduino IDE and all is working good. When I used with the external DC 5v, all the board working good except the DTH22, read 0 for temp and humidity but NRF24 work good. I try to figure what is the problem and I can't find any solution. My external DC is pluged into same terminals as the battery holders V+ and V-.

    Thanks again and sorry for my skill of english, I'm french from Quebec, Canada.

  • Hardware Contributor

    @Carl-H If you use the V+ and V- inputs which are normally used for batteries, then you may also need to bridge the BAT solder jumper on the bottom of the board, but ONLY if the battery gives 3V6 maximum.


    This will connect the 3V3 power rail to VCC.

    If you are using a FTDI interface, this one already powers VCC and via the AMS1117 also gives 3V3 to the NRF.

    The question is which V+ terminal did you use ???

    Can you post an image of your board ?

    The two inputs below give direct connection to VCC (for 5V input):


    The following inputs are for an optional DC converter, and do NOT connect to VCC.


  • Hardware Contributor

    @Carl-H I do not have any DHT22 to test and never have used them, so I do not know how you connect them.

    So I'm not sure what can be wrong. The DHT22 seems sensitive to timing according to documentation on the Adafruit website.

  • This is my board:

    0_1456440224123_dc board.jpg

    I don't want to use the bat jumber because my source is by USB plug (5v).

    My question is why is it working when I plug with my FTDI Cable (5v version).

    I will try tonight with other sensor like Si7021 but i'm pretty sure it will be working.

  • Hardware Contributor

    @Carl-H I see that you are connected to D6 (not D7 as you mentioned earlier).

  • I wrote D7 but in my sketch is D6 ;)

    #define DHT_PIN 6

  • Hero Member

    @Carl-H did you add a pull up? The DHT can be unstable without.

  • Hardware Contributor

    Added a sketch for a combination of 1 PIR, 2 relays and HTU21D Temperature/Humidity.

  • @AWI Yes I have pull up !

  • After make some test this morning I found a solution but I do not know why and what is the difference.

    I explain:

    When I used this DHT librairies (https://github.com/markruys/arduino-DHT), this one come with mysensors librairies. I can read my DHT22 sensor with my FTDI cable but is not working with from a DC 5v in, reading always 0.

    But If now I used this librairies (https://github.com/adafruit/DHT-sensor-library) , is working with FTDI cable and now with my DC 5v in.

  • Hardware Contributor

    @Carl-H Very strange indeed, but I'm glad it is sorted out.

  • @Carl-H I have used DHT11/22, DS18B20, SI7021, HTU21D, BMP180 and BME280 sensors with Arduino / Particle Photon and I can only suggest using SI7021, HTU21D and BMP180/BME280 temperature and humidity sensors. DS18B20 is very sensitive to noises and throwing temperature abnormal readings (65000C or something). DHT22 is very temperamental needless to say about the size. Also the sensors I suggested are very-very precise. BME280 being probably the most expensive.

  • @GertSanders I have a couple of your board and I will be very happy. Now I will want to try the OTA feature with this board. Did you have DualOptiboot already compiled (hex file) with D8 led pin and with 8 mhz external crystal? It will be cool you include this file like Optiboot 6.2.. Thanks

  • Hardware Contributor


    The EEPROMs on this boards are of the I2C type and this is not supported by DualOptiboot, so unfortunatly you can not use OTA on this board.

    OTA is only supported with SPI type flash memory.

    I also do not have the sourcefiles for DualOptiboot to recompile it with my D8 LED flashing. At the moment I have to concentrate on other tasks at home, but recompiling DualOptiboot to my own desires is on my TODO list for this year (I hope).

  • @GertSanders oh thanks, I have made an error... Maybe it will be working with MYSBootloader 1.3pre2 because he don't require any external memory.. Did you try before?

  • Hardware Contributor

    No, so far I have not experimented with OTA on this board or any of my boards.
    Someone has used OTA on one of my other (batterybased) boards, because that one has an SPI Flash footprint.
    When I get back to doing more MySensor stuff I will be experimenting with OTA. Being a Mac user my options are a bit limited now.

  • Hi,
    please add order number or ebay link for enclosure (box)

  • Mod

    @MiKa which box are you referring to?

    Generic boxes are available here: https://www.mysensors.org/store/boxes

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