Does the matrix voice creator have tx,rx pin?

I use RF UART CC1101 433Mhz HC-11 on raspberry, it communicates with UART, I use pin number 14 and 15 on raspberry. But when I combined with matrix voice creator, I couldn’t find its pin. I saw the pin layout of MTV but I can’t know the Uart interface pin, please help me, thank you!

Hi @tonluongdung,

Are you using the MATRIX Voice standard version? If so, the RPi’s GPIO14 and GPIO15 are unused and can be routed via the FPGA directly to MATRIX Voice expansion GPIO pins of your choice which you can then use from there.

If you are using an ESP32 version and are utilizing the ESP32, then the UART TX and RX pins are being used for communication with the ESP32 microcontroller.

If you are not using the ESP32, you can directly wire the PI_TX and PI_RX pins to 2 MATRIX Voice GPIO pins in the FPGA using the guide here.

If you can wait a day or two, I can make this change and synthesize this FPGA configuration for you, then all you would have to do is flash the new .bit configuration to the FPGA using the directions here.

Let me know what works for you!


thank you very much and sorry for my bad english I use the matrix voice creator version but yesterday ,I ordered a USB UART CP2102 to communicate with RF UART CC1101 via Usb port for raspberry, it is very effective. Maybe I don’t need to use tx vs rx pins anymore. But thanks for Your enthusiastic help. Have a nice day!

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Are you still available to make the .bit configuration with the Matrix Creator.
Otherwise, I have made an attempt using the mentioned guide with:
assign gpio_io_15 = uart_rx_pi
assign gpio_io_14 = uart_tx_pi
commented the zigbee lines that previously occupied uart_??_pi
made sure gpio_width = 14

I am trying to connect neo 6m gps module

Hi @vtu93,

Welcome to the community!

Your method make sense to me. Just remember to change the gpio names in the .ucf file and change the GPIO_WIDTH variable to 14 since you are taking up 2 pins.

Of course, in this case your zigbee module wouldn’t work, but theoretically the UART RX and TX pins from the Pi should now be connected to GPIO 14 and 15!

Have you tried any tests to see if this works with your GPS module?


I managed to get this working, I renamed the gpio names and changed around “assign gps_rx = uart_tx_pi” to “assign uart_tx_pi = gps_rx”
Thanks for the help @Samreen.

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