/*
Write a Command to the RFM Module using SPI
Requires: 16bit valid command
Returns: 16bit result from transaction
This is a bi-directional transfer.
A command is clocked out to the RFM a bit at a time.
At the same time a result is clocked back in a bit at a time.
*/
uint WriteCMD(uint CMD)
{
uint RESULT = 0; // Holds the received SDI
uchar n=16; // number of bits in SPI Command we need to send
LOW_SCK(); // SCK LOW
LOW_SEL(); // CS LOW
while(n--) // Send All 16 Bits MSB First
{
if (CMD&0x8000)
{
Write1(); // Write 1 via SDI
}
else
{
Write0(); // Write 0 via SPI
}
RESULT<<=1; // Shift left for next bit to receive
if(SDI) // Check if we received a high on SDI
RESULT |= 0x0001; // RESULT LSB = 1
CMD<<=1; // Shift left for next bit to send
}
LOW_SCK(); // SCK LOW
HI_SEL(); // CS HIGH - Finished Sending Command
return RESULT;
}
void WriteCMD(int16 CMD)
{
int8 n = 16;
output_low(_SCK);
RF_EN = false;
while (n--){
if (CMD&0x8000)
Write1();
else
Write0();
CMD<<=1;
}
SCK = false;
RF_EN = true;
}
/*
Waits for RFM 12 to become ready by checking first bit of status register
Before we can Tx or Rx data the RFM12 needs to be ready,
i.e. not in the middle of transmitting a previous byte
This function is blocking and will only return when it is ready to Tx or Rx
*/
void WaitReady(void)
{
//#ifdef DEBUG // always return for simulator
// return;
//#endif
unsigned long timeout = 0;
bit READY = 0;
while(READY == 0)
{
LOW_SCK(); // SCK LOW
LOW_SEL(); // CS LOW
Write0();
if(SDI==1) // check RGIT bit of status (first bit)
{ // If HIGH then Tx/RX is ready to accept the next byte
READY = 1;
}
LOW_SCK(); // SCK LOW
LOW_SDO();
HI_SEL(); // CS HIGH - Finished Sending Command
}
}
