Skip to content

CRSF: Allow future use of unused bits in the "Arming status byte" #7022

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
mha1 wants to merge 4 commits into
base: main
Choose a base branch
from
+35 −14
Open

CRSF: Allow future use of unused bits in the "Arming status byte" #7022

Changes from all commits
Commits
Show all changes
4 commits
Select commit Hold shift + click to select a range
1b7fb27
initial commit
mha1 Jan 15, 2026
a6406bc
make flagging crsf errors an example
mha1 Jan 15, 2026
de13f39
updated comment on bit meanings
mha1 Jan 15, 2026
2ca8d26
fix merge error
mha1 Jan 15, 2026
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
49 changes: 35 additions & 14 deletions radio/src/pulses/crossfire.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -96,20 +96,20 @@ uint8_t createCrossfireModelIDFrame(uint8_t moduleIdx, uint8_t * frame)
uint8_t createCrossfireChannelsFrame(uint8_t moduleIdx, uint8_t * frame, int16_t * pulses)
{
//
// sends channel data and also communicates commanded armed status in arming mode Switch.
// frame len 24 -> arming mode CH5: module will use channel 5
// frame len 25 -> arming mode Switch: send commanded armed status in extra byte after channel data
//
ModuleData *md = &g_model.moduleData[moduleIdx];

uint8_t armingMode = md->crsf.crsfArmingMode; // 0 = Channel mode, 1 = Switch mode
uint8_t lenAdjust = (armingMode == ARMING_MODE_SWITCH) ? 1 : 0;

// sends channel data and also communicates status information in status byte:
// - arming status in Switch mode (bit 0)
// - arming mode Switch or CH5 (bit 1)
// - bits 2-7 spare
//
uint8_t * buf = frame;
*buf++ = MODULE_ADDRESS;
*buf++ = 24 + lenAdjust; // 1(ID) + 22(channel data) + (+1 extra byte if Switch mode) + 1(CRC)
*buf++ = 25; // 1(ID) + 22(channel data) + 1(extra status byte) + 1(CRC)
uint8_t * crc_start = buf;
*buf++ = CHANNELS_ID;

//
// assemble channel data
//
uint32_t bits = 0;
uint8_t bitsavailable = 0;
for (int i=0; i<CROSSFIRE_CHANNELS_COUNT; i++) {
Expand All @@ -122,14 +122,35 @@ uint8_t createCrossfireChannelsFrame(uint8_t moduleIdx, uint8_t * frame, int16_t
bitsavailable -= 8;
}
}

if (armingMode == ARMING_MODE_SWITCH) {

//
// assemble status byte
//
ModuleData *md = &g_model.moduleData[moduleIdx];

if (md->crsf.crsfArmingMode == ARMING_MODE_SWITCH) {
swsrc_t sw = md->crsf.crsfArmingTrigger;

*buf++ = (sw != SWSRC_NONE) && getSwitch(sw, 0); // commanded armed status in Switch mode
*buf = (sw != SWSRC_NONE) && getSwitch(sw, 0); // commanded armed status in Switch mode
} else {
*buf = 0x02; // flag arming mode CH5
}

// Example: flag crsf errors to ELRS in bit 2 for resending linkstats
//
//extern bool crsfErrorFlag;
//if(crsfErrorFlag) {
// *buf |= 0x04; // flag crsf error
// crsfErrorFlag = false;
//}

buf++;

*buf++ = crc8(crc_start, 23 + lenAdjust);
//
// add crc
//
*buf++ = crc8(crc_start, 24);

return buf - frame;
}

Expand Down