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Improve HoTT code readability. Add protocol overview comments.

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This commit is contained in:
Dominic Clifton 2014-04-07 00:16:26 +01:00
parent 3ca868a59f
commit f7c937a323
1 changed files with 32 additions and 39 deletions
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71
src/telemetry_hott.c
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@ -5,6 +5,19 @@
* Author: Hydra/cGiesen
*/
/*
* HoTT is implemented in Graupner equipment using a bi-directional protocol over a single wire.
*
* Generally the receiver sends a single request byte out using normal uart signals, then waits a short period for a
* multiple byte response and checksum byte before it sends out the next request byte.
* Each response byte must be send with a protocol specific delay between them.
*
* Serial ports use two wires so connect the receiver's HoTT signal to a uart/softserial RX pin via a diode
* and then also connect a uart/softserial TX pin to the same HoTT pin on the receiver, but NOT via a diode.
*
* This is so that when baseflight transmits it does not receive it's own transmission.
*/
#include "board.h"
#include "mw.h"
@ -16,13 +29,11 @@ const uint8_t kHoTTv4TextPacketSize = 173;
static uint8_t outBuffer[173];
static void hottV4SerialWrite(uint8_t c);
static inline void hottV4EnableReceiverMode(void);
static inline void hottV4EnableTransmitterMode(void);
static void hottV4SendData(uint8_t *data, uint8_t size);
static void hottV4SendGPS(void);
static void hottV4Respond(uint8_t *data, uint8_t size);
static void hottV4FormatAndSendGPSResponse(void);
static void hottV4GPSUpdate(void);
static void hottV4SendEAM(void);
static void hottV4FormatAndSendEAMResponse(void);
static void hottV4EAMUpdateBattery(void);
static void hottV4EAMUpdateTemperatures(void);
bool batteryWarning;
@ -31,7 +42,7 @@ bool batteryWarning;
* Sends HoTTv4 capable GPS telemetry frame.
*/
void hottV4SendGPS(void)
void hottV4FormatAndSendGPSResponse(void)
{
/** Minimum data set for EAM */
HoTTV4GPSModule.startByte = 0x7C;
@ -53,7 +64,7 @@ void hottV4SendGPS(void)
memcpy(&outBuffer, &HoTTV4GPSModule, kHoTTv4BinaryPacketSize);
// Send data from output buffer
hottV4SendData(outBuffer, kHoTTv4BinaryPacketSize);
hottV4Respond(outBuffer, kHoTTv4BinaryPacketSize);
}
void hottV4GPSUpdate(void)
@ -149,7 +160,7 @@ void hottV4GPSUpdate(void)
/**
* Sends HoTTv4 capable EAM telemetry frame.
*/
void hottV4SendEAM(void) {
void hottV4FormatAndSendEAMResponse(void) {
/** Minimum data set for EAM */
HoTTV4ElectricAirModule.startByte = 0x7C;
HoTTV4ElectricAirModule.sensorID = HOTTV4_ELECTRICAL_AIR_SENSOR_ID;
@ -176,7 +187,7 @@ void hottV4SendEAM(void) {
memcpy(&outBuffer, &HoTTV4ElectricAirModule, kHoTTv4BinaryPacketSize);
// Send data from output buffer
hottV4SendData(outBuffer, kHoTTv4BinaryPacketSize);
hottV4Respond(outBuffer, kHoTTv4BinaryPacketSize);
}
/**
@ -184,15 +195,11 @@ void hottV4SendEAM(void) {
* to the HoTT capable receiver. Last byte will always be treated as checksum and is
* calculated on the fly.
*/
static void hottV4SendData(uint8_t *data, uint8_t size) {
//hottV4Serial.flush();
static void hottV4Respond(uint8_t *data, uint8_t size) {
// Protocoll specific waiting time
// to avoid collisions
delay(5);
if (serialTotalBytesWaiting(core.telemport) == 0) {
hottV4EnableTransmitterMode();
if (serialTotalBytesWaiting(core.telemport) != 0 ) {
return; // cannot respond since another request came in.
}
uint16_t crc = 0;
uint8_t i;
@ -201,15 +208,12 @@ static void hottV4SendData(uint8_t *data, uint8_t size) {
crc += data[i];
hottV4SerialWrite(data[i]);
// Protocoll specific delay between each transmitted byte
// Protocol specific delay between each transmitted byte
delayMicroseconds(HOTTV4_TX_DELAY);
}
// Write package checksum
hottV4SerialWrite(crc & 0xFF);
hottV4EnableReceiverMode();
}
}
/**
@ -217,35 +221,24 @@ static void hottV4SendData(uint8_t *data, uint8_t size) {
* If in debug mode, data is also written to UART serial interface.
*/
static void hottV4SerialWrite(uint8_t c) {
//hottV4Serial.write(c);
serialWrite(core.telemport, c);
}
/**
* Enables RX and disables TX
*/
static inline void hottV4EnableReceiverMode() {
//DDRD &= ~(1 << HOTTV4_RXTX);
//PORTD |= (1 << HOTTV4_RXTX);
}
/**
* Enabels TX and disables RX
*/
static inline void hottV4EnableTransmitterMode() {
//DDRD |= (1 << HOTTV4_RXTX);
}
void handleHoTTTelemetry(void)
{
while (serialTotalBytesWaiting(core.telemport)) {
uint8_t c = serialRead(core.telemport);
// Protocol specific waiting time
// to avoid collisions
delay(5);
switch (c) {
case 0x8A:
if (sensors(SENSOR_GPS)) hottV4SendGPS();
if (sensors(SENSOR_GPS)) hottV4FormatAndSendGPSResponse();
break;
case 0x8E:
hottV4SendEAM();
hottV4FormatAndSendEAMResponse();
break;
}
}