CC2642R: UART busy when disabled

Martin Boyd

Part Number: CC2642R
Other Parts Discussed in Thread: SIMPLELINK-CC13XX-CC26XX-SDK

I am hitting an issue when using the UARTCC26XX driver and opening and closing the UART fairly often. When UARTCC26XX_open() is called it gets stuck in an infinite loop because the FR BUSY bit is set. Any ideas how the UART could get into a bad state like this? The call stack is:

and the registers are:

SDK is simplelink_cc13x2_26x2_sdk_4_40_00_44 (yes it's old but would like to debug this first before updating as we have a lot of installs in the field and are being careful about upgrades).

It could possible be a race condition of some kind as the open and close could occur in different tasks.

over 3 years ago

+1 Ryan Brown1 over 3 years ago

TI__Guru**** 223727 points

Hi Martin,

There is a similar ticket in the SIMPLELINK-CC13XX-CC26XX-SDK v6.10, TICRIVERS-5046, where UART2_close can leave UART hardware instance UART_FR_BUSY bit set: https://software-dl.ti.com/simplelink/esd/simplelink_cc13xx_cc26xx_sdk/6.10.01.01/exports/docs/simplelink_mcu_sdk/release_notes_coresdk_cc13xx_cc26xx_6_10_00_13.html

A possible resolution path is to modify UART_close from source\ti\drivers\uart\UARTCC26X2.c to use UARTDisable instead of disabling the UART FIFO.

    /* Disable UART FIFO */
// REMOVE    HWREG(hwAttrs->baseAddr + UART_O_LCRH) &= ~(UART_LCRH_FEN);
// REMOVE    /* Disable UART module */
// REMOVE    HWREG(hwAttrs->baseAddr + UART_O_CTL) &= ~(UART_CTL_UARTEN | UART_CTL_TXE |
// REMOVE                                      UART_CTL_RXE);
    UARTDisable(hwAttrs->baseAddr);  //ADD THIS LINE

You can add the modified UARTCC26X2.c directly to your project directory so that it replaces the pre-built TI Driver library. Please give this a try and let me know whether it resolves the issue.

Regards,
Ryan

0 Martin Boyd over 3 years ago in reply to Ryan Brown1

Intellectual 810 points

This seems to have fixed the issue, thanks!

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CC2642R: UART busy when disabled