The Acme Systems shipping office will be closed for holidays from 14 august to 22 august

How to setup the serial ports inside the kernel source

Edit the file:

arch/arm/mact-at91/board-sam9x5ek.c

Inside the function ek_map_io() modify these lines:

static void __init ek_map_io(void)
{
    /* Initialize processor and DBGU */
    cm_map_io();

    at91_register_uart(AT91SAM9X5_ID_USART0, 1, 0); // USART0 on ttyS1 (only Rx,Tx)
    at91_register_uart(AT91SAM9X5_ID_USART1, 2, 0); // USART0 on ttyS2 (only Rx,Tx)
    at91_register_uart(AT91SAM9X5_ID_USART2, 3, 0); // USART0 on ttyS3 (only Rx,Tx)
    at91_register_uart(AT91SAM9X5_ID_USART3, 4, 0); // USART0 on ttyS4 (only Rx,Tx)

    at91_set_A_periph(AT91_PIN_PA1, 1);  // Pull-up on RXD0 
    at91_set_A_periph(AT91_PIN_PA6, 1);  // Pull-up on RXD1 
    at91_set_A_periph(AT91_PIN_PA8, 1);  // Pull-up on RXD2 
    at91_set_A_periph(AT91_PIN_PC23, 1); // Pull-up on RXD3 
}

Se il terzo parametro passato a at91_register_uart e' 0 vengono usati solo i segnali TXD e RXD.

Se si specificano dei valori si attivano anche i criteri se previsti dall'hardware:

  • ATMEL_UART_RTS
  • ATMEL_UART_CTS

I due valori si possono mettere in or

Le istruzioni tipo:

at91_set_A_periph(AT91_PIN_PA1, 1);  // Pull-up on RXD0 

le ho messe per attivare la resistenza di pull-up sull'RXD di ogni porta.