Guide/Tutorial/Reference about Expansion Board

[rcolistete]

Here is a long guide/tutorial/reference about all Expansion Board models :

• "Using Expansion Board" in english;
• "Usando Expansion Board", em brazilian portuguese.

Thanks to Ricardo Retsos.

"Using Expansion Board" has :

• hints & tips collected from some years of experience, Pycom forum, etc;
• detailed descriptions of features, mini-jumpers, etc;
• list of documentation from Pycom and community;
• many comparisons between the Expansion Board models;
• tutorial about installing firmware on Expansion Board v3.x;
• example source code to access user LED, user button, microSD slot, read battery voltage, etc;
• energy consumption measurements of all Expansion Board models in active/light sleep/deep sleep, with USB power supply and battery power;
• voltage measurements with USB power supply and battery power.

For example, tests with Expansion Board v3.1 with WiPy3 in :

• deep sleep mode, power from battery (Vbat = 3,61-3,66 V) :
  • 34 uA with only TX/RX mini-jumpers;
  • 102 uA with all mini-jumpers;
  • 183 uA with 8GB Sandisk UHS-I uSD and all mini-jumpers;
  • 160 uA with 16GB Toshiba M203 UHS-I uSD and all mini-jumpers;
  • 692 uA with 32GB Samsung Evo UHS-I uSD and all mini-jumpers.
    So :
  • the LED mini-jumpers adds 68 uA;
  • microSD card, just inserted, adds 58-590 uA, depending on the uSD card (not only the capacity).
• active mode, it seems a 'feature' (or bug ?) when using TX/RX mini-jumpers and battery supply (3.61-3.66 V) :
  • 34.5-35.0 ma without mini-jumpers;
  • 68.8-69.4 ma with only TX/RX mini-jumpers
  • 69.6-70.2 ma will all mini-jumpers.
    This is a 33.8-34.9 mA increase.
    But when using USB power (Vusb = 5.06-5.08 V), this issue doesn't happen, i = 43-44 mA with any mini-jumpers configuration.

[PSH_IS_NIVA]

Thanks for a great work...
Does anyone have information about version 3.2?
The jumper set has changed to 6 instead of 7: "RTS" and "CTS" are gone and a new one "RUN" is introduced.

[PSH_IS_NIVA]

On my Expansion board V3.2 the battery voltage divider seems to divide to about 60% of the battery voltage.
E.g. if the battery voltage is 3,6V then the voltage measured on the batt or P16 is about 2.1V. I checked this with a mulitmeter.

[rcolistete]

@PSH_IS_NIVA I don't have an Expansion Board v3.2, but I ordered one.

Tip : check without xxPy board connected to Expansion Board, disconnected from USB/battery power, so you can measure with the ohmmeter the 2 resistors of the voltage divider.

So, please, any information about the voltage divider or other differences in Expansion Board v3.2, feel free to share.

I don't find any Pycom documentation about Expansion Board v3.2 and its different features.

[PSH_IS_NIVA]

@rcolistete
Hmm this is confusing :/
After I read your suggestion I thought I made a mistake because I measured the voltages with also USB power connected... but then again is this really the wrong way to do it?? Well I'd say: here comes in play the lack of documentation from Pycom.... as mentioned many many times by several people in this forum :(

Anyhow...my assumption is that the divider is like this:

But that does not fit the following observations:

• With the expansion board empty and disconnected i.e. no xxPy, no battery, no USB and no BAT-jumper, I can measure R2 ( BAT-jumper <-> GND) to 0.94 Mohm but I can't measure R1 (+pin JST <-> BAT-jumper). The R1 value is not stable. My meter starts at about 2.5 Mohm but increases slowly to 2.9ish.

• With only a battery (3.6V) connected, no XXPy and no USB and no BAT-jumper I measure Vbat (+pin JST <-> GND) to 3.6V and V_R2 (BAT jumper <-> GND) to about 1.8V

• as above but with USB-power added: Vbat still 3.6V and V_R2 is now about 2.1V.

[robert-hh]

@PSH_IS_NIVA With USB connected the battery will be charged. That's why the voltage at VBat should go up.

[PSH_IS_NIVA]

@robert-hh said in Guide/Tutorial/Reference about Expansion Board:

@PSH_IS_NIVA With USB connected the battery will be charged. That's why the voltage at VBat should go up.

No it didn't. Vbat (+pin JST <-> GND) was stable on 3.6V with or without USB connected.

[kjm]

In 'Using Expansion Board' in English you state "when using FiPy or GPy with Expansion Board, remove the RTS and CTS mini-jumpers, as they conflict with the operation of the LTE modem, see CAT-M1 and NB-IoT tutorials:

1. I run a gpy on expansion board 2.0 with the RTS/CTS jumpers in place & no problems with the lte modem.
2. The clickable link to CAT-M1 doesn't seem to provide any useful detail on RTS/CTS

I'm not being critical, indeed I think any attempt to clarify pycoms chaotic documentation is laudable. But I'm still no wiser! I can't even figure out which uart the RTS/CTS jumpers apply to. Is it the uart that services the usb port or the uart that services the lte modem.

[PSH_IS_NIVA]

FYI, pictures top/bottom expansion boards v3.2:

[rcolistete]

@PSH_IS_NIVA It seems that Expansion Board v3.2 is for a specific customer, not a public release. But it was shipped by mistake to some users.

[PSH_IS_NIVA]

@rcolistete said in Guide/Tutorial/Reference about Expansion Board:
@rcolistete:

@PSH_IS_NIVA It seems that Expansion Board v3.2 is for a specific customer, not a public release. But it was shipped by mistake to some users.

Well, you may be right. As you can see from my last post here I'm of the opinion that it was just the firmware on the boards that was a incorrect version. But rereading some of correspondence - also directly with Pycom Support I'm not 100% sure any more. Only Pycom can confirm this I suppose.

Though, whether or not it is just the firmware or the hole board, our problem was fixed with just an firmware update.

[rcolistete]

See this post :
"@PSH_IS_NIVA We accidentally shipped a number of Expansion Board 3.2 that were designed for a specific customer.

Anyone who received an Expansion Board 3.2 please email support@pycom.io so we can provide a resolution."

[rcolistete]

@kjm said in Guide/Tutorial/Reference about Expansion Board:

In 'Using Expansion Board' in English you state "when using FiPy or GPy with Expansion Board, remove the RTS and CTS mini-jumpers, as they conflict with the operation of the LTE modem, see CAT-M1 and NB-IoT tutorials:

1. I run a gpy on expansion board 2.0 with the RTS/CTS jumpers in place & no problems with the lte modem.
2. The clickable link to CAT-M1 doesn't seem to provide any useful detail on RTS/CTS

I'm not being critical, indeed I think any attempt to clarify pycoms chaotic documentation is laudable. But I'm still no wiser! I can't even figure out which uart the RTS/CTS jumpers apply to. Is it the uart that services the usb port or the uart that services the lte modem.

My test with FiPy (old one) had problems with RTS/CTS jumpers, so the recommendation is correct. But I don't have GPy to confirm if the Pycom recommendation isn't needed for GPy.