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UART demo Project with UART1

Question asked by Jeremy Anderson on Aug 31, 2017
Latest reply on Sep 5, 2017 by Jeremy Anderson

I'm using the FRDM-K66F board and running the freertos_uart demo project.  It works well enough through UART0, but this is carried through the USB debug connection and I need to look at the signal on the wire.  I changed the demo project to use UART1 instead by the following steps:

1. Connect pins A9 and A11 to UART1 TX and RX by updating pin_mux.c

2. Change the DEMO_UART* symbols to refer to UART1 instead of UART0

3. Connect J1 pin 4 to pin 2 on the DE9 serial connector.

4. Connect J1 pin 2 to pin 3 on the serial connector.

5. Connect J3 pin 12 to pin 5 on the serial connector.


I can see that pin 2 on the serial connector is where I want to transmit because my script that watches the port picks up the noise when I disconnect and reconnect that wire.  I've stepped through the code and see that the UART_WriteNonBlocking function is entered and eight characters are written to the D register on each pass until the last one which only has seven.  So it seems we've done the right thing, but nothing is seen on the other end.  I can see also that the UART1 driver IRQ handler is invoked..  This really looks like a pin issue.  When I get to the receive part of the demo, the software always ends up terminating on a timeout on the event group wait.


Any experience with this out there?