/**
Sends a Module Synchronous Request (SREQ) message and retrieves the response. A SREQ is a message to
the Module that is immediately followed by a Synchronous Response (SRSP) message from the Module. As
opposed to an Asynchronous Request (AREQ) message, which does not have a SRSP. This is a private
method that gets wrapped by sendMessage() and spiPoll().
@pre Module has been initialized
@pre zmBuf contains a properly formatted message. No validation is done.
@post received data is written to zmBuf
@return if FAST_PROCESSOR is defined then MODULE_SUCCESS, else an error code. If FAST_PROCESSOR is not defined, then MODULE_SUCCESS.
*/
moduleResult_t sendSreq()
{
#ifdef FAST_PROCESSOR //NOTE: only enable if using a processor with sufficient speed (25MHz+)
uint32_t timeLeft1 = CHIP_SELECT_TO_SRDY_LOW_TIMEOUT;
uint32_t timeLeft2 = WAIT_FOR_SRSP_TIMEOUT;
SPI_SS_SET(); // Assert SS
while (SRDY_IS_HIGH() && (timeLeft1 != 0)) //wait until SRDY goes low
timeLeft1--;
if (timeLeft1 == 0) //SRDY did not go low in time, so return an error
return ZM_PHY_CHIP_SELECT_TIMEOUT;
timeFromChipSelectToSrdyLow = (CHIP_SELECT_TO_SRDY_LOW_TIMEOUT - timeLeft1);
spiWrite(zmBuf, (*zmBuf + 3)); // *bytes (first byte) is length after the first 3 bytes, all frames have at least the first 3 bytes
*zmBuf = 0; *(zmBuf+1) = 0; *(zmBuf+2) = 0; //poll message is 0,0,0
//NOTE: MRDY must remain asserted here, but can de-assert SS if the two signals are separate
/* Now: Data was sent, so we wait for Synchronous Response (SRSP) to be received.
This will be indicated by SRDY transitioning to high */
while (SRDY_IS_LOW() && (timeLeft2 != 0)) //wait for data
timeLeft2--;
if (timeLeft2 == 0)
return ZM_PHY_SRSP_TIMEOUT;
timeWaitingForSrsp = (WAIT_FOR_SRSP_TIMEOUT - timeLeft2);
//NOTE: if SS & MRDY are separate signals then can re-assert SS here.
spiWrite(zmBuf, 3);
if (*zmBuf > 0) // *bytes (first byte) contains number of bytes to receive
spiWrite(zmBuf+3, *zmBuf); //write-to-read: read data into buffer
SPI_SS_CLEAR();
return 0;
#else // In a slow processor there's not enough time to set up the timeout so there will be errors
SPI_SS_SET();
while (SRDY_IS_HIGH()) ; //wait until SRDY goes low
spiWrite(zmBuf, (*zmBuf + 3)); // *bytes (first byte) is length after the first 3 bytes, all frames have at least the first 3 bytes
*zmBuf = 0; *(zmBuf+1) = 0; *(zmBuf+2) = 0; //poll message is 0,0,0
//NOTE: MRDY must remain asserted here, but can de-assert SS if the two signals are separate
//Now: Data was sent, wait for Synchronous Response (SRSP)
while (SRDY_IS_LOW()) ; //wait for data
//NOTE: if SS & MRDY are separate signals then can re-assert SS here.
spiWrite(zmBuf, 3);
if (*zmBuf > 0) // *bytes (first byte) contains number of bytes to receive
spiWrite(zmBuf+3, *zmBuf); //write-to-read: read data into buffer
SPI_SS_CLEAR(); // re-assert MRDY and SS
return MODULE_SUCCESS;
#endif
}
/*************************************************************************
Setup hardware SPI in Master mode
Input: none
Returns: none
*************************************************************************/
void SPI_master_setup(void)
{
SPI_PORT.DIR |= SPI_MOSI | SPI_SS | SPI_CLK;
SPI_SS_SET();
SPI.CTRL = SPI_ENABLE_bm | SPI_MASTER_bm | SPI_MODE_3_gc | SPI_PRESCALER_DIV4_gc | SPI_CLK2X_bm;
SPI.INTCTRL = SPI_INTLVL_OFF_gc;
}
/** From znp_interface_spi.c, implemented here to avoid pesky dependencies */
signed int sendSreq()
{
SPI_SS_SET();
while (SRDY_IS_HIGH()) ; //wait until SRDY goes low
spiWrite(znpBuf, (*znpBuf + 3)); // *bytes (first byte) is length after the first 3 bytes, all frames have at least the first 3 bytes
*znpBuf = 0; *(znpBuf+1) = 0; *(znpBuf+2) = 0; //poll message is 0,0,0
//SPI_SS_CLEAR(); //NOTE: MRDY must remain asserted here, but can de-assert SS if the two signals are separate
while (SRDY_IS_LOW()) ; //wait for data
//SPI_SS_SET(); //NOTE: if SS & MRDY are separate signals then can re-assert SS here.
spiWrite(znpBuf, 3);
if (*znpBuf > 0) // *bytes (first byte) contains number of bytes to receive
spiWrite(znpBuf+3, *znpBuf); //write-to-read: read data into buffer
SPI_SS_CLEAR();
return 0;
}
