/*!
* Read SPI device ID.
*
* \param id Three byte character array, which receives
* the CPU ID.
*/
void SpiFlashId(u_char * id)
{
u_char i;
for (i = 0; i < 3; i++) {
SpiByte(0x30);
SpiByte(0x00);
SpiByte(i);
id[i] = SpiByte(0x00);
}
}
/*!
* \brief Read memory chip status.
*/
static uint8_t SpiMemStatus(uint8_t cs)
{
uint8_t rc;
if (cs == SPIMEM_CS_BIT) {
sbi(SPIMEM_CS_PORT, cs);
} else {
cbi(SPIMEM_CS_PORT, cs);
}
SpiByte(0x57);
rc = SpiByte(0);
if (cs == SPIMEM_CS_BIT) {
cbi(SPIMEM_CS_PORT, cs);
} else {
sbi(SPIMEM_CS_PORT, cs);
}
return rc;
}
/*!
* \brief Write byte to the target's flash memory.
*
* The target must have been erased by a previous call
* to SpiFlashErase().
*
* \param high Must be 0 to write the low byte or 8 to
* write the high byte.
* \param addr Word address to write to.
* \param data Byte value to write.
*
* \return 0 on success, -1 otherwise.
*/
int SpiFlashWriteByte(u_char high, u_short addr, u_char data)
{
u_char d;
if (data != 0xff) {
SpiByte(0x40 | high);
SpiByte(addr >> 8);
SpiByte(addr & 0xFF);
SpiByte(data);
/*
* During programming a value of 0x7F appears at the memory location.
* If we are programming this value, we delay execution by 10 ms.
* Otherwise we poll the memory location until we read back the
* programmed value.
*/
if (data == 0x7f)
NutDelay(10);
else {
for (d = 0; d < 255; d++) {
/*
* Read program flash byte.
*/
SpiByte(0x20 | high);
SpiByte(addr >> 8);
SpiByte(addr & 0xFF);
if (SpiByte(0xFF) == data)
break;
}
if (d == 255)
return -1;
}
}
/*!
* \brief Enable SPI device flash programming.
*
* \return 0 if device could be located, -1 otherwise.
*/
int SpiFlashEnable(void)
{
u_char i;
u_char rc;
/*
* PB0(O): SS
* PB1(O): SCK
* PB2(O): MOSI
* PB3(I): MISO
*
* PB4(O): Reset target
* PB5(-): Unused
* PB6(-): Unused
* PB7(-): Unused
*/
/*
* SCK and MOSI outputs need configuration,
* even if SPI mode is enabled.
*/
cbi(PORTB, 1);
sbi(DDRB, 1);
cbi(PORTB, 2);
sbi(DDRB, 2);
/*
* Enable pull-up on MISO.
*/
sbi(PORTB, 3);
for (i = 0; i < 32; i++) {
/*
* Set reset low.
*/
cbi(PORTB, 4);
sbi(DDRB, 4);
/*
* Set slave select pin to output. Otherwise a low signal
* on this pin might force us to SPI slave mode.
*/
sbi(DDRB, 0);
outp(BV(MSTR) | BV(SPE) | BV(SPR0), SPCR);
/*
* Try to enable programming.
*/
SpiByte(0xAC);
SpiByte(0x53);
rc = SpiByte(0xFF);
SpiByte(0xff);
if (rc == 0x53)
return 0;
/*
* Programming enable failed. This may be because the
* target is not synchronized. A positive pulse on the
* clock line should help.
*/
outp(0, SPCR);
sbi(PORTB, 1);
cbi(PORTB, 1);
}
return -1;
}
