Hi all !
I would like to get SPI to work in LW_Mesh.
I'm using ATZB-A24-UFLB and used pins for that are:
38 -> USART0_RXD
39 -> USART0_TXD
40 -> USART0_EXTCLK
and my CS -> chip select.
I used SPI ni BitCloud without any problems and had a look how it's implemented but I'm kind of lost there.
So I'm trying to implement SPI this way:
In datasheet of ATmega1281 p. 235 & 237 I found these code examples:
void USART_Init( unsigned int baud )
{
UBRRn = 0;
/* Setting the XCKn port pin as output, enables master mode. */
XCKn_DDR |= (1<<XCKn);
/* Set MSPI mode of operation and SPI data mode 0. */
UCSRnC = (1<<UMSELn1)|(1<<UMSELn0)|(0<<UCPHAn)|(0<<UCPOLn);
/* Enable receiver and transmitter. */
UCSRnB = (1<<RXENn)|(1<<TXENn);
/* Set baud rate. */
/* IMPORTANT: The Baud Rate must be set after the transmitter is enabled
*/
UBRRn = baud;
}
unsigned char USART_Receive( void )
{
/* Wait for empty transmit buffer */
while ( !( UCSRnA & (1<<UDREn)) );
/* Put data into buffer, sends the data */
UDRn = data;
/* Wait for data to be received */
while ( !(UCSRnA & (1<<RXCn)) );
/* Get and return received data from buffer */
return UDRn;
}
I have few questions here:
1. Here we are talking about USART0, since real SPI is used for AT86RF230, so everywhere in code above "n" is replaced with "0", right?
I don't quite understand this line:
/* Setting the XCKn port pin as output, enables master mode. */ XCKn_DDR |= (1<<XCKn);
AS6 doesn't recognize "XCKn_DDR" register, do I have to include something or ??
What I think what is happening here is:
USART0_EXTCLK(PE2) is used as clock and set as output.
So insted of :
/* Setting the XCKn port pin as output, enables master mode. */ XCKn_DDR |= (1<<XCKn);
I can use:
DDRE |= (1<<PE2);
2. AS6 doesn't recognize "UDORD0" in UCSR0C register.
I need SPI in MSPIM mode, SPI mode 1 and MSB first
It's better to do it like this:
UCSR0C = 0xC2;
insted of:
UCSR0C = (1<<UMSELn1)|(1<<UMSELn0)|(1<<UCPHAn)|(0<<UCPOLn)|(0<<UDORD0);
Will this code above work with required modifications or is there better way to do it?
Thanks !
