the UART port on an AT91SAM7S-EK board. I haven't been able
out. This is the code I'm using to set the whole thing up:
int main (void)
{
// Initialize the clock
init();
// enable the USART peripheral clock
volatile AT91PS_PMC pPMC = AT91C_BASE_PMC; // pointer to PMC data structure
pPMC->PMC_PCER = (1<<AT91C_ID_US0);
USART_init();
// send loop
while (1)
{
transmit(hello);
// Delay
volatile long int i = 0;
for(; i < 10000000; ++i);
}
}
void init(void)
{
AT91PS_PMC pPMC = AT91C_BASE_PMC;
//* Set Flash Wait sate
AT91C_BASE_MC->MC_FMR = ((AT91C_MC_FMCN)&(47 <<16)) | AT91C_MC_FWS_1FWS;
//* Watchdog Disable
AT91C_BASE_WDTC->WDTC_WDMR= AT91C_WDTC_WDDIS;
// 1 Enabling the Main Oscillator:
pPMC->PMC_MOR = (( AT91C_CKGR_OSCOUNT & (0x06 <<8) | AT91C_CKGR_MOSCEN ));
// Wait the startup time
while(!(pPMC->PMC_SR & AT91C_PMC_MOSCS));
// Main Clock (MAINCK from crystal oscillator) = 18432000 hz (see AT91SAM7-EK schematic)
// PLLCK = 1228800 * (MUL + 1) = 1228800 * (74 + 1) = 1228800 * 75 = 92160000 hz
pPMC->PMC_PLLR = ((AT91C_CKGR_DIV & 15) |
(AT91C_CKGR_PLLCOUNT & (10<<8)) |
(AT91C_CKGR_MUL & (74<<16)));
// Wait the startup time (until PMC Status register LOCK bit is set)
while(!(pPMC->PMC_SR & AT91C_PMC_LOCK));
// PMC Master Clock (MCK) Register setup
// Note: Master Clock MCK = 46080000 hz (this is the CPU clock speed)
// result: AT91C_PMC_MCKR = 0x00000007 (Master Clock Register)
pPMC->PMC_MCKR = AT91C_PMC_CSS_PLL_CLK | AT91C_PMC_PRES_CLK_2;
}
void USART_init(void)
{
AT91PS_USART usart = AT91C_BASE_US0;
// Disable PIOA control over pin, enabling USART control
*AT91C_PIOA_PDR = (AT91C_PA0_RXD0 | /* Enable RxD0 Pin */
AT91C_PA1_TXD0); /* Enalbe TxD0 Pin */
*AT91C_PIOA_ASR = (AT91C_PA0_RXD0 | /* Enable RxD0 Pin */
AT91C_PA1_TXD0); /* Enalbe TxD0 Pin */
*AT91C_PIOA_PPUER = (AT91C_PA0_RXD0 | /* Enable pull-up */
AT91C_PA1_TXD0);
usart->US_CR = (AT91C_US_RSTRX | /* Reset Receiver */
AT91C_US_RSTTX | /* Reset Transmitter */
AT91C_US_RXDIS | /* Receiver Disable */
AT91C_US_TXDIS);
usart->US_MR = (AT91C_US_CHRL_8_BITS |
AT91C_US_USMODE_NORMAL |
AT91C_US_SYNC |
4 << 9); // No parity
usart->US_BRGR = MCK/115200; /* = 115200 baud */
usart->US_CR = (AT91C_US_RXEN | /* Receiver Enable */
AT91C_US_TXEN); /* Transmitter Enable */
}
void transmit(char *str)
{
AT91PS_USART usart = AT91C_BASE_US0;
int i = 0;
do
{
while(usart->US_CSR & AT91C_US_TXRDY == 0);
usart->US_THR = str[i];
} while(str[i++]);
return;
}
I've got my board hooked up to the serial port of a Linux computer through a null modem cable. The serial port is configured as follows:
Anyways, any help with this would be greatly appreciated.
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