Skip to content

DSM: Add extra XPlus channels to protocol #1138

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

Draft
wants to merge 2 commits into
base: master
Choose a base branch
from
Draft

DSM: Add extra XPlus channels to protocol #1138

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
cd381f1
Add extra XPlus channels to DSM protocol
frankiearzu Nov 6, 2025
0fd0529
By default, keep respecting the THR_KILL functionality (CH14)
frankiearzu Nov 7, 2025
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
55 changes: 44 additions & 11 deletions Multiprotocol/DSM_cyrf6936.ino
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -20,7 +20,10 @@
//#define DSM_DEBUG_FWD_PGM
//#define DEBUG_BIND 1

#define CLONE_BIT_MASK 0x20
#define CLONE_BIT_MASK 0x20
#define MODE_11MS_BIT_MASK 0x40
#define MAX_THROW_BIT_MASK 0x80

#define DSM_BIND_CHANNEL 0x0D //13 This can be any odd channel
#define DSM2_SFC_PERIOD 16500

Expand Down Expand Up @@ -51,6 +54,12 @@ enum {
DSM_CH2_READ_B,
};

#if defined(DSM_X_PLUS)
#define XP_CH CH13 // X-Plus channel placeholder in frame
uint8_t x_plus_ch = 0; // X-Plus channel currently multiplexing
#else
#define XP_CH 0xff // No Channel
#endif
//
uint8_t ch_map[14];
const uint8_t PROGMEM DSM_ch_map_progmem[][14] = {
Expand All @@ -65,7 +74,7 @@ const uint8_t PROGMEM DSM_ch_map_progmem[][14] = {
{1, 5, 2, 3, 6, 0xff, 0xff, 4, 0, 7, 8, 0xff, 0xff, 0xff}, //9ch - Guess
{1, 5, 2, 3, 6, 0xff, 0xff, 4, 0, 7, 8, 9, 0xff, 0xff}, //10ch - Guess
{1, 5, 2, 3, 6, 10, 0xff, 4, 0, 7, 8, 9, 0xff, 0xff}, //11ch - Guess
{1, 5, 2, 4, 6, 10, 0xff, 0, 7, 3, 8, 9 , 11 , 0xff}, //12ch - DX18/DX8G2
{1, 5, 2, 4, 6, 10, XP_CH, 0, 7, 3, 8, 9 , 11 , 0xff}, //12ch - DX18/DX8G2
//11ms for 8..11 channels
{1, 5, 2, 3, 6, 7, 0xff, 1, 5, 2, 4, 0, 0xff, 0xff}, //8ch - DX7
{1, 5, 2, 3, 6, 7, 0xff, 1, 5, 2, 4, 0, 8, 0xff}, //9ch - Guess
Expand Down Expand Up @@ -148,7 +157,7 @@ static void __attribute__((unused)) DSM_update_channels()

// Create channel map based on number of channels and refresh rate
uint8_t idx=num_ch-3;
if((option & 0x40) && num_ch>7 && num_ch<12)
if((option & MODE_11MS_BIT_MASK) && num_ch>7 && num_ch<12)
idx+=5; // In 11ms mode change index only for channels 8..11
for(uint8_t i=0;i<14;i++)
ch_map[i]=pgm_read_byte_near(&DSM_ch_map_progmem[idx][i]);
Expand Down Expand Up @@ -199,20 +208,23 @@ static void __attribute__((unused)) DSM_build_data_packet(uint8_t upper)
}
#endif

#ifdef DSM_THROTTLE_KILL_CH
#if defined(DSM_THROTTLE_KILL_CH)
uint16_t kill_ch=Channel_data[DSM_THROTTLE_KILL_CH-1];
#endif
for (uint8_t i = 0; i < 7; i++)
{
uint8_t idx = ch_map[(upper?7:0) + i]; // 1,5,2,3,0,4
uint16_t value = 0xffff;
if((option&0x40) == 0 && num_ch < 8 && upper)

if((option & MODE_11MS_BIT_MASK) == 0 && num_ch < 8 && upper)
idx=0xff; // in 22ms do not transmit upper channels if <8, is it the right method???
if (idx != 0xff)

else
if (idx != 0xff)
{
/* Spektrum own remotes transmit normal values during bind and actually use this (e.g. Nano CP X) to
select the transmitter mode (e.g. computer vs non-computer radio), so always send normal output */
#ifdef DSM_THROTTLE_KILL_CH
#if defined(DSM_THROTTLE_KILL_CH)
if(idx==CH1 && kill_ch<=604)
{//Activate throttle kill only if channel is throttle and DSM_THROTTLE_KILL_CH below -50%
if(kill_ch<CHANNEL_MIN_100) // restrict val to 0...400
Expand All @@ -223,17 +235,38 @@ static void __attribute__((unused)) DSM_build_data_packet(uint8_t upper)
}
else
#endif
{
#if defined(DSM_X_PLUS)
if (idx==XP_CH) { // X-Plus special channel placeholder
idx = XP_CH + x_plus_ch; // Encode CH13-CH16 instead
}
#endif
#ifdef DSM_MAX_THROW
value=Channel_data[CH_TAER[idx]]; // -100%..+100% => 1024..1976us and -125%..+125% => 904..2096us based on Redcon 6 channel DSM2 RX
#else
if(option & 0x80)
if(option & MAX_THROW_BIT_MASK)
value=Channel_data[CH_TAER[idx]]; // -100%..+100% => 1024..1976us and -125%..+125% => 904..2096us based on Redcon 6 channel DSM2 RX
else
value=convert_channel_16b_nolimit(CH_TAER[idx],0x156,0x6AA,false); // -100%..+100% => 1100..1900us and -125%..+125% => 1000..2000us based on a DX8 G2 dump
#endif
if(bits==10) value>>=1;
value |= (upper && i==0 ? 0x8000 : 0) | (idx << bits);
}
}

#if defined(DSM_X_PLUS)
if (idx >= XP_CH) { // X-Plus Channel
// Multiplexing 4 chanels on the same frame channel placeholder for channel 13 (ID=12) over time (Refresh cycle 88ms)
// CH13-16 lower frame, and Ch17-20 upper. We only do lower right now, since MM cannot handle more than 16ch
// Channel value is 9 bits, and upper 2 bits is the X-Plus channel (CH13..CH16).
value >>= 2; // Convert to 9 bits
value |= (XP_CH << 11) | (x_plus_ch << 9); // constant 12 (4 bits), XPlus Ch (2 bits), Value (9 bits)
x_plus_ch = (x_plus_ch + 1) % 4; // only 0..3
} else
#endif
{ // Regular channel
if(bits==10) value>>=1;
value |= (upper && i==0 ? 0x8000 : 0) | (idx << bits);
}
}

packet[i*2+2] = value >> 8;
packet[i*2+3] = value;
}
Expand Down
2 changes: 1 addition & 1 deletion Multiprotocol/Multiprotocol.h
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -19,7 +19,7 @@
#define VERSION_MAJOR 1
#define VERSION_MINOR 3
#define VERSION_REVISION 4
#define VERSION_PATCH_LEVEL 52
#define VERSION_PATCH_LEVEL 53

#define MODE_SERIAL 0

Expand Down
4 changes: 4 additions & 0 deletions Multiprotocol/_Config.h
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -294,6 +294,7 @@
//The DSM protocol is using by default the Spektrum throw of 1100..1900us @100% and 1000..2000us @125%.
// For more throw, 1024..1976us @100% and 904..2096us @125%, remove the "//" on the line below. Be aware that too much throw can damage some UMX servos. To achieve standard throw in this mode use a channel weight of 84%.
//#define DSM_MAX_THROW

//Some models (X-Vert, Blade 230S...) require a special value to instant stop the motor(s).
// You can disable this feature by adding "//" on the line below. You have to specify which channel (14 by default) will be used to kill the throttle channel.
// If the channel 14 is above -50% the throttle is untouched but if it is between -50% and -100%, the throttle output will be forced between -100% and -150%.
Expand All @@ -303,6 +304,9 @@
//Enable DSM Forward Programming
#define DSM_FWD_PGM

//Enable X-Plus channels, Ch13-16.. if Enabled, will still respect the DSM_THROTTLE_KILL_CH feature
#define DSM_X_PLUS

/**************************/
/*** FAILSAFE SETTINGS ***/
/**************************/
Expand Down