What board should I choose for this BLE sensor tag?

Development Platforms
1

Hi,

In my past experience with PlatformIO, I have been using development board such as Arduino or ESP32 series, whose name I can find an exact match from the dev board’s product page when creating a new PlatformIO project.

However, I am trying to burn my own code into this sensor tag. I only know that the MCU is NRF51822, but I see a lot board options by PlatformIO, and they all have the same MCU.

Can anyone help me determine which board I should choose to set up the PlatformIO configuration for this project?

Also, I see four pins named “CLK”, “DIO”, “VCC”, “GND” on this sensor tag. I am wondering how I can connect them to my computer to transfer my code onto the MCU. For dev boards like Arduino, there was microUSB ports I can use, which is not the case for this one.

Thank you very much for your help!

2

The DIO and CLK are the SWD signals (also called SWDIO and SWCLK). You need a SWD-capable programmer to program it, e.g., a JLink or an ST-Link or a CMSIS-DAP or Blackmagic probe.

And of course via VCC and GND you can feed it power. Since I don’t see a voltage regulator on the board, you should feed VCC = 3.3V (or rather, anything from 1.8V to 3.6V per datasheet page 34) directly in it (e.g. from the STLink or JLink plus a voltage regulator, since by default it only outputs +5V). The board alternatively has a CRCR2032 (3.0V) coin holder, if you put a battery in, you just need to connect GND between the programmer and the board, but not VCC.

The item also shows that a 16MHz crystal is on board, and PIO shows boards with 32MHz and 16MHz. I’m not sure if the chip contains a PLL and is still capable of going to 32MHz with a 16 MHz crystal, but to be safe, maybe choose a board with 16MHz speed first or change the frequency in the platformio.ini.

You can e.g. try this board and given that you have connected it to a JLink:

[env:redBearLabBLENano]
platform = nordicnrf51
board = redBearLabBLENano
framework = arduino
board_build.f_cpu = 16000000L
upload_protocol = jlink
debug_tool = jlink

Note that there is no USB-UART converter on this board, so if you want to see serial outupt, you will have to use your own USB-UART converter and connect it to that board.

However, it has an RGB LED on-board per the schematics linked in this post that calls the board " NRF51 Sensor Tag", with LEDR,G,B being mapped to nRF pins P0_17, P0_18, P0_19, and if I read the arduino pin mapping for the above board correctly, then LEDR is D7, or just “pin 7”, meaing you should try the most simple blinky example

#include <Arduino.h>
#define LED 7
void setup() {
  pinMode(LED, OUTPUT);
}

void loop() {
  digitalWrite(LED, HIGH);
  delay(1000);
  digitalWrite(LED, LOW);
  delay(1000);
}

first.

If the pin mapping of the above board is insufficient, use the Generic variant instead by adding

board_build.variant = Generic

to the platformio.ini, then “P0_19” = digital pin 19, et cetera.

3

Thank you very much! I will give it a try!

4

Hi! Sorry for the super late reply. I only got a chance to continue what I was working on recently.

I have tried your suggested board setting in platformio.ini while having my board connected to my PC through a JTAG cable, but the code still failed to upload. (I tried both when I power it with a CRCR2032 battery and 3.3V external power supply)

For my JTAG cable, I actually don’t know which wire is SWDIO and which is SWCLK, so I tried both connection combinations, but neither worked.

(BTW I don’t think JTAG cable is the proper way to call it, but I was told it’s a “JTAG” when I got the cable. It looks like the size of a USB flash drive with 4 extended wires.)

Here are the errors I got using different upload protocols:

  1. Jlink

    982×518 27 KB

  2. cmsis-dap

    1096×414 49 KB

  3. stlink

    1090×506 51.5 KB

  4. blackmagic

    1092×288 35.9 KB

Also, when I check my device manager, it only displays the board device in the “Port” but not in the USB section. I think the error might be caused by some bad connection. Any help is appreciated! Thanks in advance!