2 years, 11 months ago.

Serial port Tx problem.

Just got this kit along with MAX32620FTHR kit and found that the separate DAP programmer boards are also usable, very impressed!

I want to connect a serial Wi-Fi module ESP8266. I have a full functioning ESP8266 driver library that includes a buffered serial driver :


This works faultless (I'm using Mbed 2) with all my ST and NXP and Si-Labs boards but won't work with either of these boards. ( I have set the pin Vcc's to 3.3v).

Trying various code examples I find Serial Tx and Rx is working with some Oled displays and GPS modules, however when I try Serial Attach IRQ functions it goes wrong. Sometimes it will run for a while and I get Rx and Tx data then it stops and finally I get MCU lock out. I get nothing using the Buffered Serial code.

Could you guys advise please.

Thank you


Question relating to:

MAX32630 Rapid Development Platform

1 Answer

2 years, 3 months ago.

If you receive for a while with your Rx IRQ and then you get MCU lock out, I would suspect that you aren't reading the incoming stream fast enough and you are letting the receive buffer overflow.

void rxirq () {                      // UART Receive IRQ
    char c;
    while (uart.readable()) {
        rLED = !rLED;          // Toggle LED so we can see the action
        c = uart.getc();
        ... Do something with char; put it in your buffer, etc.
        ... Process the buffer somewhere else, like a thread.

Unfortunately its a bit more involved.

Maxim appear not to be supporting their products on Mbed, there are currently 239 warnings during compiling using the latest Mbed-os.

Running SerialPassthrough :


will only work up to 115200, just, and that is with VIO_3V3 set.

SerialPassthrough works up to 921600 on all my other platforms. There's a problem with the Serial API on Maxims platforms, the MAX32620FTHR and MAX32625PICO have exactly the same issue.

posted by Paul Staron 05 Oct 2019