Starting out to try some simple measurements, I would like to use some analog pins.

It would be nice to have a chart of pins that are already in use by the built in features, such as battery voltage.
This is mentioned in the literature, but it's spread out in several different places.

The literature says:
"The extension headers provide direct access to the MCU pins. Pins already in use by the Whisper Node board will have their function displayed as [BOARD_USED]. Board functions displayed as (BOARD_OPTIONAL) are optional and not connected by default."

However I have not found the board used and board optional anywhere so far ?? Did I miss it ?

Hi Randykarr.

First sorry for the delay, for some reason I didn't get a notification about this new topic.

About the Whisper Node Pinouts, if you have a look on the ASCII board drawing, you'll find the pin numbers as well the usage as [use] or (use). The square brackets are connected by default.
The "optional" ones are (RTC_VIN) and (RTC_INT), they are not connected to the MCU and they need to be connected via a "Solder Jumper" if required.

Many of the other pins already connected to the MCU can be modified via solder jumper or removing components. Have a look on this part of the documentation: https://bitbucket.org/talk2/whisper-nod ... figuration and let me know if you have any question.

Pins from that are not marked as [USED] on the ASCII drawing above are free to use. Saying that you still can use, for example, the LED and BTN pins as OUTPUT/INPUT without changing anything. Just have a look on the circuit details on the documentation to make sure it's compatible with your project.

Cheers,
Mike M.

Based on this, is it a correct assumption that only 3 digital pins are good to use without modification? D0, D1, and D3. Or would the button pins also fall into this category, assuming you don't want to use the buttons? For the LED pins, using them as an OUTPUT would also trigger the LED, unless modifications are done.

Am I tracking properly?

-j

Hi jfeger,

Yes and no... D0 and D1 are used by the Serial Port, so you can only use if you don't need the Serial Communication like Serial.println(). But remember that all Analog Ports work as digital port as well (with exception of except A6 and A7).

Without physically modifying the board you can use:

D3, A1, A2, A3, A4 and A5.
Those pins are directly connected from the header to the MCU pin without any circuit in between.

D4 and D5
Additionally, without modifying the board, you can use D4 and D5 as de-bounced Inputs with pull-down resistors. Those are ideal to any low frequency switch or inputs with any kind of interference. The rising time is around 0.5ms and the falling time is about 8.0ms. In other words, good for up to 1KHz.

The D4 and D5 can also be used as low-frequency Output without modification, the only detail is that you'll have a 110K path to ground. In other words, it'll drain some small current (33uA) when you "digitalWrite(HIGH)" in addition to whatever you'll be driving. So remember if you're design low-power applications.

D6 and D9
The LEDs pins D6 and D9 can also be used as Outputs, just need to consider the LED current draw when writing "HIGH" (about 3-5mA), which should be ok if you're driving short pulses or not using for low-power applications.

The SPI Lines
I haven't tested myself, but in theory you should be able to use the pins D11, D12 and D13 as INPUT or OUTPUT without affecting the RFM69 neither the SPI Flash. Just need to make sure the "Slave Select" of each external device is kept HIGH when doing that(D10 and D8). Also those ports NEVER should go over 3.3V.

D0 and D1
As mentioned before those are the TX and RX lines for the UART (Serial). This is used during the firmware upload and also for communication, normally debug - for example "Serial.println()". If you don't plan to use the hardware Serial from the MCU, those lines can be used as GPIO.

If the available Pins above are not enough, you can free additional ones:

A0, A6, A7 and D7
Those pins have exposed PCB jumpers on the back of the board which can be cut to break the circuit. Have a look on the following link for more details: https://bitbucket.org/talk2/whisper-nod ... figuration, juste remember that A6 and A7 are analog inputs only.

Finally, if that still not enough the only option is to desolder/break LEDs off and the resistors + capacitors of each button so you can have pin with no components attached.

Cheers

Perfect timing on this post. I hadn't dug into what pins were already being used and had just copied some code I'd been using before on another project, using D9. Couldn't figure out why the LED was lighting up and was coming out here this weekend to ask, so thanks for beating me to it!

Hi there,
I wanted to ask one small query. What is the highest voltage the analog pin (A0) is able to take in ? 
I have a sensor whose output is 0 to 5 V and I want to feed that into A0 but I could not find any document that mentions the voltage range of the analog pins.

I would really appreciate any help.

Regards

Hi BirajBhandari, although the A0 pin would support 5V as the ATMega328P is a 5V MCU, the maximum reference voltage is 3.3V, or 1.1V if you use the "Internal". I would recommend to use a voltage divider and bring the voltage to be read between 0 and 1V. Ths way you can use the Internal reference.

Talk2 wrote: ↑

Feb 11, 2017

Hi jfeger,

Yes and no... D0 and D1 are used by the Serial Port, so you can only use if you don't need the Serial Communication like Serial.println(). But remember that all Analog Ports work as digital port as well (with exception of except A6 and A7).

Without physically modifying the board you can use:

D3, A1, A2, A3, A4 and A5.
Those pins are directly connected from the header to the MCU pin without any circuit in between.

D4 and D5
Additionally, without modifying the board, you can use D4 and D5 as de-bounced Inputs with pull-down resistors. Those are ideal to any low frequency switch or inputs with any kind of interference. The rising time is around 0.5ms and the falling time is about 8.0ms. In other words, good for up to 1KHz.

The D4 and D5 can also be used as low-frequency Output without modification, the only detail is that you'll have a 110K path to ground. In other words, it'll drain some small current (33uA) when you "digitalWrite(HIGH)" in addition to whatever you'll be driving. So remember if you're design low-power applications.

D6 and D9
The LEDs pins D6 and D9 can also be used as Outputs, just need to consider the LED current draw when writing "HIGH" (about 3-5mA), which should be ok if you're driving short pulses or not using for low-power applications.

The SPI Lines
I haven't tested myself, but in theory you should be able to use the pins D11, D12 and D13 as INPUT or OUTPUT without affecting the RFM69 neither the SPI Flash. Just need to make sure the "Slave Select" of each external device is kept HIGH when doing that(D10 and D8). Also those ports NEVER should go over 3.3V.

D0 and D1
As mentioned before those are the TX and RX lines for the UART (Serial). This is used during the firmware upload and also for communication, normally debug - for example "Serial.println()". If you don't plan to use the hardware Serial from the MCU, those lines can be used as GPIO.

If the available Pins above are not enough, you can free additional ones:

A0, A6, A7 and D7
Those pins have exposed PCB jumpers on the back of the board which can be cut to break the circuit. Have a look on the following link for more details: https://bitbucket.org/talk2/whisper-nod ... figuration, juste remember that A6 and A7 are analog inputs only.

Finally, if that still not enough the only option is to desolder/break LEDs off and the resistors + capacitors of each button so you can have pin with no components attached.

Cheers

Solution with D11, D12. D13 is a wonderful solution that helped me with my problem. Thanks for the detailed explanation.