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Subject [GitHub] [incubator-nuttx] patacongo opened a new issue #1092: LPC17_40: UART set the buadrate jump to the Infinite loop
Date Wed, 20 May 2020 13:11:41 GMT

patacongo opened a new issue #1092:

   This was Issue 173 in the old Bitbucket repository
   Former user
   created an issue 2019-10-09
   In arch/arm/src/lpc17xx_40xx/lpc17_40_serial.c, function ioctrl:
       lcr = getreg32(priv->uartbase + LPC17_40_UART_LCR_OFFSET);
       up_serialout(priv, LPC17_40_UART_LCR_OFFSET, (lcr | UART_LCR_DLAB));
       /* Set the BAUD divisor */
       #ifdef LPC176x
         dl = lpc17_40_uartdl(priv->baud, priv->cclkdiv);
         dl = lpc17_40_uartdl(priv->baud);
        up_serialout(priv, LPC17_40_UART_DLM_OFFSET, dl >> 8);
        up_serialout(priv, LPC17_40_UART_DLL_OFFSET, dl & 0xff);
       /* Clear DLAB */
       up_serialout(priv, LPC17_40_UART_LCR_OFFSET, lcr);
   the DLAB can only write during the uart reg 0x7C USR bit 0 is clear。 when the uart is
busy the setting will cause the IIR[3:0] = 0111
   UART_16550_COMPATIBLE = NO and master has tried to write to the Line Control Register while
the DW_apb_uart is busy (USR[0] is set to 1).

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