Arduino Nano 33 BLE Sense vs Arduino Uno vs USB-to-TTL

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1

Hello.

I am new to Arduino professionally speaking and I got a new job where I'm going to work with Arduinos and a lot of sensors.

So, the scenario is the following:

At work I have an Arduino Nano 33 BLE Sense, an ESP-01 WiFi module and an USB-to-TTL converter based on a CG340H chip.

Long sotry short:
I can program the ESP-01 chip using the USB-to-TTL converter. I get a COMx port on Windows Dev Manager and everything wroks as expected. I added a PROG push-button in the back of the USB-to-TTL converter to switch the ESP-01 between RUN and PROG modes.

If I try to use the Arduino Nano 33 BLE Sense to program the same ESP-01 module, using 2 push buttons for the PROG/RUN modes switching and for the RESET, I can't upload any firmware to the ESP-01 module. I can only change between RUN/PROG modes and perform the RESET.

So, to troubleshoot this issue I have taken 32 voltage measurements like this:
USB-to-TTL + ESP-01 => RUN mode
USB-to-TTL + ESP-01 => PROG mode
then
Arduino Nano 33 BLE Sense + ESP-01 => RUN mode
Arduino Nano 33 BLE Sense + ESP-01 => PROG mode

8 measurements for the 8 pins of the ESP-01.
They are like this:

So, the biggest ifference I found is that using the USB-to-TTL converter, I have 5V (both in RUN an PROG modes) at RxD pin while using the Arduino Nano 33 Sense, I have 3.08V and 0V.

Now, at home, I have an Arduino Uno (v3 iirc) and one other ESP8266 board. Link to an image of this board.
In this scenario, I can program the ESP8266 based board only chnaging the red switch pins to switch between PROG and RUN modes.

So, knowing this, I have a couple of questions I cannot answer with great amount of certainty.
1 - Using USB-to-TTL converter I get a COMx port in Windows Dev Manager (at work). Using the Arduino Nano 33 BLE Sense, I don't get any COMx port probably because according to a tutorial I was follwoing (for Arduino Uno), the Arduino board needs to be in RESET state.
Are we supposed to get a COMx port using the USB-to-TTL converter but not with the Arduino Nano 33 BLE Sense in RESET state???

2 - If we are not supposed to get a COMx port using the Arduino Nano 33 BLE Sense, how is supposed Arduino IDE to upload code to the ESP-01, like the tutorial shows?

3 - Is the ESP-01 (the one I have at work) / ESP8266 based board (the one I have at home) supposed to work on 5V at its RxD pin or not?

My first conclusion is that the ESP-01/ESP8266 based board needs 5V at least at the RxD pin to be able to get code, which the Arduino Nano 33 BLE Sense cannot provide, therefore not being able to upload code with it. However, using my home Arduino and my work USB-to-TTL converter I can upload code to the ESP-01 / ESP8266 based board and measure around 5V at the WiFi modules (both home and work) RxD pins.

Can anyone help me with this?

Edite 1;
Just a note: at home I don't use Windows. I use Debian BullsEye.

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That tutorial does not mention Nano 33BLE, it uses an Uno. They are different boards with different chips.

When Uno is held in RESET state, it is the main atmega328 chip that is in RESET state. Uno also has a separate USB-serial chip, and that is free to operate normally when the main chip is in RESET. This chip can then act as a USB-serial for your ESP.

Nano 33BLE's main chip is a nRF52840. This chip has "native" USB capability built-in. It does not need, and so the board does not have, a separate USB-serial chip. When you put the Nano 33BLE in RESET state, the main chip cannot act as a USB-serial adaptor for your ESP.

I don't know if it's possible to use Nano 33BLE to program your ESP. It may be possible, but not using the same technique as you can with Uno.

My advice would be to get a separate USB-serial adapter to use at home.

1 Like
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I know the tutorial doesn't mention the Nano 33 BLE Sense. I was aware of that.
What I didn't know and didn't read about was what you mention of Nano 33 BLE Sense not having a separate USB-to-TTL chip and therefore, not being possible to use it like the Uno board is used.

Thank you for the reply.
Psy

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