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LAUNCHCC3220MODASF: Can't get BOOSTXL-RS232 to work

Other Parts Discussed in Thread: CC3220SF, BOOSTXL-RS232

I have a prototype application running on the Launchpad. The code is based on the mqtt_client_CC3220SF_LAUNCHXL_tirtos_ccs example. Everything works great when connected to the PC via the micro USB cable. I can publish and subscribe, hibernate and wake up, and communicate via the virtual COM port via the USB cable. My next step is to run off of battery and will still need to communicate via a UART. I purchased the BOOSTXL-RS232. I have GP3 jumpered from J7 to J8, GP4 from J5 to J6, GP5 on J7, and GP12 on J5, On the Launchpad, I short J5 & J6 to route the UART signals to the 20 pin connector. I also found that I have to change the SOP jumper from 010 to 001 in order to get my program to run when powered by battery instead of USB. Anyway, my program runs... LEDs light as I would expect and I can connect to the broker via Wi-Fi. However, I can't communicate via the UART. The RTS LED is green once connected to a PC, the CTS LED flashes green when my program tries to transmit via the UART. However, I don't receive anything in my terminal on the PC and when I try to transmit via the PC, the module doesn't appear to receive. The TX and RX LEDs stay red at all times. Did I miss a step somewhere? I figured by moving those UART jumpers and attaching the BOOSTXL-RS232 board, the communications would shift to the RS232 board. Is there another jumper somewhere or do I need to make a change in software?

  • Richard,

    I believe there are voltage translators after that jumper on the xds side to ensure the uart works correctly. i would check the voltage levels needed for your RS232 boosterpack and make sure that is not the issue.

    Can you try using our device plugged into usb and also using the RS232 boosterpack? This could help us hone in on the issue.

  • Thanks for the response. I spent all day, but I was able to sort it out...

    The LaunchPad Hardware User's Guide (swru512) defines P1.3 (GPIO_13) as UART0_RX and P1.4 (GPIO_12) as UART0_TX. The BOOSTXL_RS232 Hardware User's Guide (sllu250) lists default jumper positions as TX2 (GP3), RX2 (GP4), RTS2 (GP5), and CTS2 (GP8). Its says these are typical settings on the TI LaunchPads and that correlates to the LaunchPad documentation I referenced.

    However, when reviewing the LaunchPad schematic (WCS028A(CC3220SFM)_sch), I found that UART_TX is actually routed to GPIO_02 and UART_RX is routed to GPIO_01. GPIO_01 comes off the LaunchPad on P2.9 which is GP12 on the BOOSTXL. GPIO_02 (sort of) comes off the LaunchPad on P3.3 which is not selectable via the jumpers on the BOOSTXL. Plus, there is some analog input circuitry at the P3.3 pin that requires R86 to be removed and R83 to be shorted. Instead, I just ran a wire from J6 pin 2 on the LaunchPad to TX on the BOOSTXL. That, plus the jumper on the BOOSTXL from RX to GP12 was "all" it took. I'm able to transmit and receive now.

    I kind of expected this to be plug and play and I certainly didn't think I'd have to work so hard to figure it out, but it's working. I hope my efforts might help someone else.