Why is the BLE device not starting on my Arduino Pro Mini?

Question

I recently purchased a 5V arduino pro mini that I now wish to connect to a BLE device.

I firstly tried the BLE device with my Uno board and it worked very well! However when I now try to use it on my mini it does not start.

This is my wiring: First I connect the pro mini to the uno in order to upload the code looking like this:

1. Arduino Mini Pro to Arduino Uno

2. RX --> TX

3. TX --> RX
4. VCC --> 5v
5. GND --> GND
6. RST --> RST

Then I wire the mini to my BLE device (https://learn.adafruit.com/getting-started-with-the-nrf8001-bluefruit-le-breakout/hooking-everything-up):

1. Arduino Mini Pro to BLE nRF8001

2. 13 --> SCK

3. 12 --> MISO
4. 11 --> MOSI
5. 10 --> REQ
6. 9 --> RST
7. 2 --> RDY
8. GND --> GND
9. VCC --> VIN

When I connect this setup to the computer the arduino uno starts and also the pro mini (both has LED lights on). I upload a simple test code that worked when i tried it with the uno but the BLE device does not respond (it seems like it does not turn on) when i use it with the pro mini.

Any idea what might be wrong? I have my board put as: Arduino Pro or Pro Mini, ATmega328 (5V, 16 MHz).

Thanks a ton!! :)

Answer 1

This is my wiring: First I connect the pro mini to the uno in order to upload the code looking like this:

Arduino Mini Pro to Arduino Uno
RX --> TX
TX --> RX
VCC --> 5v
GND --> GND
RST --> RST

How would this work? The bootloader in the Uno and Mini Pro will both try to reply. You need a FTDI or a USB-to-UART module instead of the Uno. Alternatively, start by programming the Uno to act as a USB-to-UART converter using Serial and SoftwareSerial.

Cheers!

• Martman: I saw the connection from this thread: instructables.com/id/SpeechVoice-Controlled-Arduino-Drone/… Check under "Step 1". I also found this thread that has similiar connection: instructables.com/id/…
• Martman: But maybe it will not work to use the Uno as a "code-uploader". I have this at home also: youtube.com/watch?v=59VHCXNxSvQ Check minute 1.56. I have the red one. Would that work with the Pro mini?
• Mikael Patel: The second link is fine. The MCU on the Arduino Uno is removed and the board is used as a USB-to-UART. The first link is an SMD AVR MCU and the trick might be the 3.3V setting. The Mini Pro is using 5V.
• Martman: Ah ok. I do not have a big MCU/Atmel on my current arduino (i got a chinese copy) and i assume it will be hard to remove it. Did you see the youtube-video, do you think that could work with the pro mini to upload code? It has GND, RXD, TXD and VDD pins
• Mikael Patel: Yes, the Arduino IDE setting should be the target board. In this case the Pro Mini. Check frequency (8 or 16 MHz) and voltage (3.3V or 5V).