/**
* @brief Reads RSI message from RS-485 bus, checks CRC
*
* @param fd File descriptor for RSI session (UART)
* @param buffer Buffer to hold read message
*
* @return
*/
uInt16_t rsi_read( uInt16_t fd, uInt8_t *buffer )
{
if (fd == -1) return -1;
uInt16_t count;
sInt32_t validRsiFrame = STATUS_FAILURE;
tcflush(fd, TCIFLUSH); //in half duplex mode, ignore chars we sent and may have received...
rs485_rcvEnable();
while (validRsiFrame != STATUS_SUCCESS) {
//rs485UartVminVtime( fd, 0, 0 ); //no block
buffer[0] = 0;
// wait for RSI SOF...
do
{
count = rs485_read(fd, buffer, 1);
if (count < 0) puts("-");
delayuS(10); //don't burn up all the CPU if nonblocking read enabled
if (count == -1 && errno != EAGAIN) //FIXME needs work
puts("unhandled read error!\n");
} while (buffer[0] != RSI_SOF);
rs485UartVminVtime( fd, RSI_MAX_FRAME_SIZE, 1 ); //wait for max size frame (or) 0.1 sec timeout
//now capture remainder of packet. length is not fully known!
// if bit 7 of Type = 1: indicates 2 length bytes
// Length bytes indicates # data bytes
// tricky: FCS can be one or 2 bytes, not always indicated by cmd Type!!
//BETTER?: if we can rely on intercharacter timeout (0.1 sec) then
// ask for max cmd size & wait for timeout...
//KERNEL BUG? current timeout appears to be about 2 seconds (?)
count = rs485_read(fd, &buffer[1], RSI_MAX_FRAME_SIZE-1); //should return after 0.1 sec
printf("total bytes counted = %d\n", count+1);
//RS485 Bytes received
dbg_print_msg( 0, buffer, count+1 );
//validate message CRC/checksum
validRsiFrame = rsi_validateFrame( &buffer[1], count);
} //waiting for validRsiFrame
//gpio_setValue( RS485_LED_RED, 0 );
rs485_rcvDisable();
return (count+1);
}
/**
* @brief Writes RSI message to RS-485 bus
*
* @param fd File descriptor for RSI session
* @param buffer Buffer containing message to write
* @param numBytes Number of bytes to write
*
* @return
*/
uInt16_t rsi_write( uInt16_t fd, uInt8_t *buffer, uInt16_t numBytes )
{
if (fd == -1) return -1;
rs485_xmitEnable(); //half duplex mode, enable Tx
rs485_write( fd, buffer, numBytes );
tcdrain(fd); //FIXME: force the write to complete - do we need it?
dbg_print_msg( 1, buffer, numBytes );
//FIXME! at 9600 baud, need to ensure Tx is done before disabling transceiver!
delayuS(100000); //9600 baud * 64 bytes max = 66 mS ==> wait 100 mSec
rs485_xmitDisable();
}
void u8g_MicroDelay(void)
{
delayuS(1);
}
void u8g_10MicroDelay(void)
{
delayuS(10);
}
void u8g_Delay(uint16_t val)
{
delayuS(1000UL * (uint32_t)val);
}