157 lines
4.0 KiB
C++
157 lines
4.0 KiB
C++
/*
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* Copyright (C) OpenTX
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*
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* Based on code named
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* th9x - http://code.google.com/p/th9x
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* er9x - http://code.google.com/p/er9x
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* gruvin9x - http://code.google.com/p/gruvin9x
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*
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* License GPLv2: http://www.gnu.org/licenses/gpl-2.0.html
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*/
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#include "opentx.h"
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#define BITLEN_SBUS (10*2) // 100000 Baud => 10uS per bit
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/* The protocol reuse some the DSM2 definitions where they are identical */
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#if defined(PPM_PIN_SERIAL)
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void sendByteSbus(uint8_t b)
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{
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uint8_t parity = 1;
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putDsm2SerialBit(0); // Start bit
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for (uint8_t i=0; i<8; i++) { // 8 data Bits
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putDsm2SerialBit(b & 1);
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parity = parity ^ (b & 1);
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b >>= 1;
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}
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putDsm2SerialBit(!parity); // Even Parity bit
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putDsm2SerialBit(1); // Stop bit
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putDsm2SerialBit(1); // Stop bit
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}
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#else
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static void _send_level(uint8_t v)
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{
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/* Copied over from DSM, this looks doubious and in my logic analyzer
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output the low->high is about 2 ns late */
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if (extmodulePulsesData.dsm2.index & 1)
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v += 2;
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else
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v -= 2;
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*extmodulePulsesData.dsm2.ptr++ = v - 1;
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extmodulePulsesData.dsm2.index+=1;
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extmodulePulsesData.dsm2.rest -=v;
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}
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void sendByteSbus(uint8_t b) // max 11 changes 0 10 10 10 10 P 1
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{
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bool lev = 0;
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uint8_t parity = 1;
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uint8_t len = BITLEN_SBUS; //max val: 10*20 < 256
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for (uint8_t i=0; i<=9; i++) { //8Bits + 1Parity + Stop=1
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bool nlev = b & 1; //lsb first
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parity = parity ^ (uint8_t)nlev;
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if (lev == nlev) {
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len += BITLEN_SBUS;
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}
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else {
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_send_level(len);
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len = BITLEN_SBUS;
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lev = nlev;
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}
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b = (b>>1) | 0x80; //shift in ones for stop bit and parity
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if (i==7)
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b = b ^ parity; // lowest bit is one from previous line
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}
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_send_level(len+ BITLEN_SBUS); // enlarge the last bit to be two stop bits long
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}
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#endif
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#define SBUS_NORMAL_CHANS 16
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#define SBUS_CHAN_BITS 11
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/* Definitions from CleanFlight/BetaFlight */
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#define SBUS_FLAG_CHANNEL_17 (1 << 0)
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#define SBUS_FLAG_CHANNEL_18 (1 << 1)
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#define SBUS_FLAG_SIGNAL_LOSS (1 << 2)
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#define SBUS_FLAG_FAILSAFE_ACTIVE (1 << 3)
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#define SBUS_FRAME_BEGIN_BYTE 0x0F
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#define SBUS_CHAN_CENTER 992
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inline int getChannelValue(uint8_t port, int channel)
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{
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int ch = g_model.moduleData[port].channelsStart+channel;
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// We will ignore 17 and 18th if that brings us over the limit
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if (ch > 31)
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return 0;
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return channelOutputs[ch] + 2 * PPM_CH_CENTER(ch) - 2*PPM_CENTER;
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}
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void setupPulsesSbus()
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{
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#if defined(PPM_PIN_SERIAL)
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extmodulePulsesData.dsm2.serialByte = 0;
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extmodulePulsesData.dsm2.serialBitCount = 0;
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#else
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extmodulePulsesData.dsm2.rest = SBUS_PERIOD_HALF_US;
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extmodulePulsesData.dsm2.index = 0;
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#endif
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extmodulePulsesData.dsm2.ptr = extmodulePulsesData.dsm2.pulses;
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// Sync Byte
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sendByteSbus(SBUS_FRAME_BEGIN_BYTE);
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uint32_t bits = 0;
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uint8_t bitsavailable = 0;
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// byte 1-22, channels 0..2047, limits not really clear (B
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for (int i=0; i<SBUS_NORMAL_CHANS; i++) {
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int value = getChannelValue(EXTERNAL_MODULE, i);
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value = value*8/10 + SBUS_CHAN_CENTER;
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bits |= limit(0, value, 2047) << bitsavailable;
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bitsavailable += SBUS_CHAN_BITS;
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while (bitsavailable >= 8) {
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sendByteSbus((uint8_t) (bits & 0xff));
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bits >>= 8;
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bitsavailable -= 8;
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}
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}
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// flags
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uint8_t flags=0;
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if (getChannelValue(EXTERNAL_MODULE, 16) > 0)
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flags |= SBUS_FLAG_CHANNEL_17;
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if (getChannelValue(EXTERNAL_MODULE, 17) > 0)
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flags |= SBUS_FLAG_CHANNEL_18;
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sendByteSbus(flags);
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// last byte, always 0x0
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sendByteSbus(0x00);
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putDsm2Flush();
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}
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