avr: improve the L2/L3 protocol on the SPI interface
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0e2405b496
commit
4d5a3a2a39
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@ -19,32 +19,33 @@
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//
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// $Id$
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#include <avr/io.h> // include I/O definitions (port names, pin names, etc)
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#include <avr/interrupt.h> // include interrupt support
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#include <avr/io.h>
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#include <avr/interrupt.h>
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#include "uart.h" // include uart function library
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#include "uart.h"
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#include "spi.h"
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#include "ctrl.h"
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#define NO_OP_1 1
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#define NO_OP_2 2
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#define TRANSMIT 4
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#define HIGH_HEX 8
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#define TO_FROM_UART 16
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#define NEW_CTRL_MSG 32
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#define START_TX 4
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#define TRANSMIT 8
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#define HIGH_HEX 16
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#define TO_FROM_UART 32
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#define NEW_CTRL_MSG 64
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#define SPI_END_OF_TX 0x00
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#define SPI_END_OF_MESSAGE ':'
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#define SPI_END_OF_MESSAGE '.'
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#define SPI_FORWARD_TO_UART_PORT 'u'
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#define SPI_FORWARD_TO_CTRL_PORT 'l' // 'l'ocal port
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volatile uint8_t high_hex;
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volatile uint8_t spi_status;
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volatile uint8_t spi_status, high_hex;
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// hex to binary/byte decoding
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uint8_t htob(uint16_t hex) {
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uint8_t htob(uint16_t hex)
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{
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uint8_t low_hex = (uint8_t) hex;
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uint8_t high_hex = (uint8_t) (hex >> 8);
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uint8_t byte;
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@ -56,7 +57,8 @@ uint8_t htob(uint16_t hex) {
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}
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// binary/byte to hex encoding
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uint16_t btoh(uint8_t byte) {
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uint16_t btoh(uint8_t byte)
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{
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uint8_t low_nibble = (byte & 0x0F);
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uint8_t high_nibble = (byte & 0xF0) >> 4;
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uint16_t hex;
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@ -68,8 +70,10 @@ uint16_t btoh(uint8_t byte) {
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}
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SIGNAL(SPI_STC_vect) {
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uint8_t spi_rx, spi_tx, uart_tx;
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ISR(SPI_STC_vect)
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{
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uint8_t spi_rx, rx, tx;
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uint16_t spi_tx;
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// the SPI is double-buffered, requiring two NO_OPs when switching from Tx to Rx
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if (spi_status & (NO_OP_1 | NO_OP_2)) {
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@ -77,38 +81,58 @@ SIGNAL(SPI_STC_vect) {
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return;
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}
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// do we have to transmit the first byte?
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if (spi_status & START_TX) {
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received_from_spi(SPI_FORWARD_TO_CTRL_PORT);
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spi_status &= ~START_TX;
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return;
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}
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// are we in Tx mode?
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if (spi_status & TRANSMIT) {
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if (spi_status & TO_FROM_UART) {
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if (spi_status & HIGH_HEX) {
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received_from_spi(high_hex);
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spi_status &= ~HIGH_HEX;
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return;
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}
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}
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else {
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if (ctrlGetFromTxBuffer(&spi_tx)) {
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received_from_spi(spi_tx);
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}
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else {
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if (spi_status & TO_FROM_UART) {
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if (!uartReceiveByte(&tx)) {
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received_from_spi(SPI_END_OF_TX);
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spi_status &= ~TRANSMIT;
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spi_status |= NO_OP_2;
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uartAddToTxBuffer('r'); //debugging
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return;
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}
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}
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else {
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if (ctrlGetFromTxBuffer(&tx)) {
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if (tx == SPI_END_OF_MESSAGE) {
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received_from_spi(tx);
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return;
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}
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}
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else {
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received_from_spi(SPI_FORWARD_TO_UART_PORT);
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spi_status |= TO_FROM_UART;
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return;
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}
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}
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spi_tx = btoh(tx);
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high_hex = (uint8_t)spi_tx;
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spi_status |= HIGH_HEX;
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received_from_spi((uint8_t)(spi_tx >> 8));
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return;
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}
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// we're in Rx mode
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switch (spi_rx = received_from_spi(0x00)) {
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case SPI_END_OF_TX:
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spi_status |= TRANSMIT;
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spi_status |= TRANSMIT | START_TX;
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spi_status &= ~(HIGH_HEX | TO_FROM_UART);
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uartAddToTxBuffer('t'); //debugging
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break;
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case SPI_END_OF_MESSAGE:
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if (spi_status & TO_FROM_UART) {
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spi_status &= ~TO_FROM_UART;
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}
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else {
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if (!(spi_status & TO_FROM_UART)) {
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ctrlAddToRxBuffer(spi_rx);
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spi_status |= NEW_CTRL_MSG;
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}
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@ -120,57 +144,60 @@ SIGNAL(SPI_STC_vect) {
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spi_status &= ~TO_FROM_UART;
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break;
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default:
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//check whether the incoming hex-encoded stream needs to be forwarded to the UART port
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if (spi_status & TO_FROM_UART) {
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if (spi_status & HIGH_HEX) {
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uart_tx = htob(((uint16_t)high_hex << 8) + spi_rx);
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uartAddToTxBuffer(uart_tx);
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rx = htob(((uint16_t)high_hex << 8) + spi_rx);
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if (spi_status & TO_FROM_UART) {
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uartAddToTxBuffer(rx);
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}
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else {
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ctrlAddToRxBuffer(rx);
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}
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}
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else {
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high_hex = spi_rx;
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}
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// toggle to the HEX bit in spi_status
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// toggle the HEX bit in spi_status
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spi_status ^= HIGH_HEX;
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}
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else {
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// forward to CTRL_RX buffer
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ctrlAddToRxBuffer(spi_rx);
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}
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}
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}
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int main(void) {
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ISR(TIMER1_COMPA_vect)
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{
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/* void */
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}
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int main(void)
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{
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// Configure PD5=DE as output pin with low as default
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DDRD |= (1<<DDD5);
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// Timer1 clock prescaler set to 1 => fTOV1 = 3686.4kHz / 65536 = 56.25Hz (DS p.134)
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TCCR1B |= (1<<CS10);
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// Increase sampling frequency to 2kHz (= 667Hz per channel) with an error of 0.01% (DS p.122)
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OCR1A = 0x0732;
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// Timer1 set to CTC mode (DS p.133)
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TCCR1B |= 1<<WGM12;
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// Enable output compare match interrupt for timer1 (DS p.136)
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TIMSK1 |= (1<<OCIE1A);
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#if DBG > 0
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// Set PB1=OC1A as output pin
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DDRB |= (1<<DDB1);
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// Toggle pin OC1A=PB1 on compare match
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TCCR1A |= 1<<COM1A0;
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#endif
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// initialize the CTRL buffers
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ctrlInit();
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// initialize the UART buffers with a default UART baud rate of 4800
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// initialize the UART hardware and buffers
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uartInit();
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// initialize the SPI in slave mode
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setup_spi(SPI_MODE_0, SPI_MSB, SPI_INTERRUPT, SPI_SLAVE);
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uint8_t data;
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uint16_t send;
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for(;;) {
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if (uartReceiveByte(&data)) {
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// check the HEX bit in spi_status
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if (spi_status & HIGH_HEX) {
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// loopback on the UART itf
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send = btoh(htob(((uint16_t)high_hex << 8) + data));
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uartAddToTxBuffer((uint8_t)(send >> 8));
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uartAddToTxBuffer((uint8_t)(send));
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}
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else {
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high_hex = data;
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}
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// toggle to the HEX bit in spi_status
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spi_status ^= HIGH_HEX;
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}
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if (spi_status & NEW_CTRL_MSG) {
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ctrlLoop();
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ctrlRxToTxLoop();
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spi_status &= ~NEW_CTRL_MSG;
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}
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}
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