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goebish/CX10_Blue_PCB.ino

Last active February 1, 2026 23:35
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Cheerson CX-10 Tx Arduino Code (blue PCB)
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CX10_Blue_PCB.ino
// Update : a xn297 is not required anymore, it can be emulated with a nRF24l01 :
// https://gist.github.com/goebish/ab4bc5f2dfb1ac404d3e
// **************************************************************
// ****************** CX-10 Tx Code (blue PCB) ******************
// by goebish on RCgroups.com
// based on green pcb cx-10 TX code by closedsink on RCgroups.com
// based largely on flysky code by midelic on RCgroups.com
// Thanks to PhracturedBlue, hexfet, ThierryRC
// Hasi for his arduino PPM decoder
// **************************************************************
// Hardware any M8/M168/M328 setup(arduino promini,duemilanove...as)
// !!! take care when flashing the AVR, the XN297 RF chip supports 3.6V max !!!
// !!! use a 3.3V programmer or disconnect the RF module when flashing. !!!
// !!! XN297 inputs are not 5 Volt tolerant, use a 3.3V MCU or logic level !!!
// !!! adapter or voltage divider on MOSI/SCK/CS/CE if using 5V MCU !!!
// DIY CX-10 RF module - XN297 and circuitry harvested from *BLUE* CX-10 controller
// pinout: http://imgur.com/a/unff4
// XN297 datasheet: http://www.foxware-cn.com/UploadFile/20140808155134.pdf
//Spi Comm.pins with XN297/PPM, direct port access, do not change
#define PPM_pin 2 // PPM in
#define MOSI_pin 5 // MOSI-D5
#define SCK_pin 4 // SCK-D4
#define CS_pin 6 // CS-D6
#define CE_pin 3 // CE-D3
#define MISO_pin 7 // MISO-D7
//---------------------------------
// spi outputs
#define CS_on PORTD |= 0x40 // PORTD6
#define CS_off PORTD &= 0xBF // PORTD6
#define CE_on PORTD |= 0x08 // PORTD3
#define CE_off PORTD &= 0xF7 // PORTD3
//
#define SCK_on PORTD |= 0x10 // PORTD4
#define SCK_off PORTD &= 0xEF // PORTD4
#define MOSI_on PORTD |= 0x20 // PORTD5
#define MOSI_off PORTD &= 0xDF // PORTD5
// spi input
#define MISO_on (PIND & 0x80) // PORTD7
//
#define NOP() __asm__ __volatile__("nop")
#define PACKET_LENGTH 19
#define PACKET_INTERVAL 6 // interval of time between start of 2 packets, in ms
#define PPM_MIN 1000
#define PPM_MAX 2000
// PPM stream settings
#define CHANNELS 6
enum chan_order{ // TAER -> Spektrum/FrSky chan order
THROTTLE,
AILERON,
ELEVATOR,
RUDDER,
AUX1, // mode
AUX2, // flip control
};
//########## Variables #################
static uint8_t aid[4]={0xFF,0xFF,0xFF,0xFF}; // aircraft ID
static uint8_t txid[4]; // transmitter ID
static uint8_t freq[4]; // frequency hopping table
static uint8_t packet[PACKET_LENGTH];
volatile uint16_t Servo_data[CHANNELS] = {0,};
int ledPin = 13;
void setup() {
randomSeed((analogRead(A0) & 0x1F) | (analogRead(A1) << 5));
for(uint8_t i=0;i<4;i++) {
txid[i] = random();
}
txid[1] %= 0x30;
freq[0] = (txid[0] & 0x0F) + 0x03;
freq[1] = (txid[0] >> 4) + 0x16;
freq[2] = (txid[1] & 0x0F) + 0x2D;
freq[3] = (txid[1] >> 4) + 0x40;
pinMode(ledPin, OUTPUT);
//PPM input from transmitter port
pinMode(PPM_pin, INPUT);
//RF module pins
pinMode(MOSI_pin, OUTPUT);
pinMode(SCK_pin, OUTPUT);
pinMode(CS_pin, OUTPUT);
pinMode(CE_pin, OUTPUT);
pinMode(MISO_pin, INPUT);
digitalWrite(ledPin, LOW);//start LED off
CS_on;//start CS high
CE_on;//start CE high
MOSI_on;//start MOSI high
SCK_on;//start sck high
delay(70);//wait 70ms
CS_off;//start CS low
CE_off;//start CE low
MOSI_off;//start MOSI low
SCK_off;//start sck low
delay(100);
CS_on;//start CS high
delay(10);
//############ INIT1 ##############
CS_off;
_spi_write(0x3f); // Set Baseband parameters (debug registers) - BB_CAL
_spi_write(0x4c);
_spi_write(0x84);
_spi_write(0x67);
_spi_write(0x9c);
_spi_write(0x20);
CS_on;
delayMicroseconds(5);
CS_off;
_spi_write(0x3e); // Set RF parameters (debug registers) - RF_CAL
_spi_write(0xc9);
_spi_write(0x9a);
_spi_write(0xb0);
_spi_write(0x61);
_spi_write(0xbb);
_spi_write(0xab);
_spi_write(0x9c);
CS_on;
delayMicroseconds(5);
CS_off;
_spi_write(0x39); // Set Demodulator parameters (debug registers) - DEMOD_CAL
_spi_write(0x0b);
_spi_write(0xdf);
_spi_write(0xc4);
_spi_write(0xa7);
_spi_write(0x03);
CS_on;
delayMicroseconds(5);
CS_off;
_spi_write(0x30); // Set TX address 0xCCCCCCCC
_spi_write(0xcc);
_spi_write(0xcc);
_spi_write(0xcc);
_spi_write(0xcc);
_spi_write(0xcc);
CS_on;
delayMicroseconds(5);
CS_off;
_spi_write(0x2a); // Set RX pipe 0 address 0xCCCCCCCC
_spi_write(0xcc);
_spi_write(0xcc);
_spi_write(0xcc);
_spi_write(0xcc);
_spi_write(0xcc);
CS_on;
delayMicroseconds(5);
_spi_write_address(0xe1, 0x00); // Clear TX buffer
_spi_write_address(0xe2, 0x00); // Clear RX buffer
_spi_write_address(0x27, 0x70); // Clear interrupts
_spi_write_address(0x21, 0x00); // No auto-acknowledge
_spi_write_address(0x22, 0x01); // Enable only data pipe 0
_spi_write_address(0x23, 0x03); // Set 5 byte rx/tx address field width
_spi_write_address(0x25, 0x02); // Set channel frequency
_spi_write_address(0x24, 0x00); // No auto-retransmit
_spi_write_address(0x31, PACKET_LENGTH); // 19-byte payload
_spi_write_address(0x26, 0x07); // 1 Mbps air data rate, 5dbm RF power
_spi_write_address(0x50, 0x73); // Activate extra feature register
_spi_write_address(0x3c, 0x00); // Disable dynamic payload length
_spi_write_address(0x3d, 0x00); // Extra features all off
MOSI_off;
delay(100);//100ms delay
//############ INIT2 ##############
if(_spi_read_address(0x10) != 0xCC) // reads 1 byte of Transmit address
; // we have a problem ....
_spi_write_address(0x20, 0x0e); // Power on, TX mode, 2 byte CRC
MOSI_off;
delay(50);//50ms delay
//**********************************************************************
//PPM setup
attachInterrupt(PPM_pin - 2, read_ppm, CHANGE);
TCCR1A = 0; //reset timer1
TCCR1B = 0;
TCCR1B |= (1 << CS11); //set timer1 to increment every 1 us @ 8MHz, 0.5 us @16MHz
//
delay(50);
//Bind to Receiver
bind_XN297();
}
//############ MAIN LOOP ##############
void loop() {
for (int chan = 0; chan < 4; chan++) {
uint32_t nextPacket = millis()+PACKET_INTERVAL;
CE_off;
delayMicroseconds(5);
_spi_write_address(0x20, 0x0e); // TX mode
_spi_write_address(0x25, freq[chan]); // Set RF chan
_spi_write_address(0x27, 0x70); // Clear interrupts
_spi_write_address(0xe1, 0x00); // Flush TX
Write_Packet(0x55); // servo_data timing is updated in interrupt (ISR routine for decoding PPM signal)
while(millis() < nextPacket) {} // wait
}
}
//BIND_TX
void bind_XN297() {
byte counter=255;
bool bound=false;
while(!bound){
CE_off;
delayMicroseconds(5);
_spi_write_address(0x20, 0x0e); // Power on, TX mode, 2 byte CRC
_spi_write_address(0x25, 0x02); // set RF channel 2
_spi_write_address(0x27, 0x70); // Clear interrupts
_spi_write_address(0xe1, 0x00); // Flush TX
Write_Packet(0xaa); // send bind packet
delay(2);
_spi_write_address(0x27, 0x70); // Clear interrupts
_spi_write_address(0x25, 0x02); // Set RF channel
_spi_write_address(0x20, 0x0F); // Power on, RX mode, 2 byte CRC
CE_on; // RX mode
uint32_t timeout = millis()+4;
while(millis()<timeout) {
if(_spi_read_address(0x07) == 0x40) { // data received
CE_off;
Read_Packet();
aid[0] = packet[5];
aid[1] = packet[6];
aid[2] = packet[7];
aid[3] = packet[8];
if(packet[9]==1) {
bound=true;
break;
}
}
}
CE_off;
digitalWrite(ledPin, bitRead(--counter,3)); //check for 0bxxxx1xxx to flash LED
}
digitalWrite(ledPin, HIGH);//LED on at end of bind
}
//-------------------------------
//-------------------------------
//XN297 SPI routines
//-------------------------------
//-------------------------------
void Write_Packet(uint8_t init){//24 bytes total per packet
uint8_t i;
CS_off;
_spi_write(0xa0); // Write TX payload
_spi_write(init); // packet type: 0xaa or 0x55 aka bind packet or data packet)
_spi_write(txid[0]);
_spi_write(txid[1]);
_spi_write(txid[2]);
_spi_write(txid[3]);
_spi_write(aid[0]); // Aircraft ID
_spi_write(aid[1]);
_spi_write(aid[2]);
_spi_write(aid[3]);
// channels data
if (Servo_data[5] > 1500)
bitSet(Servo_data[3], 12);// Set flip mode based on chan6 input
cli(); // disable interrupts
packet[0]=lowByte(Servo_data[AILERON]);//low byte of servo timing(1000-2000us)
packet[1]=highByte(Servo_data[AILERON]);//high byte of servo timing(1000-2000us)
packet[2]=lowByte(Servo_data[ELEVATOR]);
packet[3]=highByte(Servo_data[ELEVATOR]);
packet[4]=lowByte(Servo_data[THROTTLE]);
packet[5]=highByte(Servo_data[THROTTLE]);
packet[6]=lowByte(Servo_data[RUDDER]);
packet[7]=highByte(Servo_data[RUDDER]);
sei(); // enable interrupts
for(i=0;i<4;i++){
_spi_write(packet[0+2*i]);
_spi_write(packet[1+2*i]);
}
// Set mode based on chan5 input
if (Servo_data[4] > 1800)
i = 0x02;// mode 3
else if (Servo_data[4] > 1300)
i = 0x01;// mode 2
else
i= 0x00;// mode 1
_spi_write(i);
_spi_write(0x00);
MOSI_off;
CS_on;
CE_on; // transmit
}
void Read_Packet() {
uint8_t i;
CS_off;
_spi_write(0x61); // Read RX payload
for (i=0;i<PACKET_LENGTH;i++) {
packet[i]=_spi_read();
}
CS_on;
}
void _spi_write(uint8_t command) {
uint8_t n=8;
SCK_off;
MOSI_off;
while(n--) {
if(command&0x80)
MOSI_on;
else
MOSI_off;
SCK_on;
NOP();
SCK_off;
command = command << 1;
}
MOSI_on;
}
void _spi_write_address(uint8_t address, uint8_t data) {
CS_off;
_spi_write(address);
NOP();
_spi_write(data);
CS_on;
}
// read one byte from MISO
uint8_t _spi_read()
{
uint8_t result=0;
uint8_t i;
MOSI_off;
NOP();
for(i=0;i<8;i++) {
if(MISO_on) // if MISO is HIGH
result = (result<<1)|0x01;
else
result = result<<1;
SCK_on;
NOP();
SCK_off;
NOP();
}
return result;
}
uint8_t _spi_read_address(uint8_t address) {
uint8_t result;
CS_off;
_spi_write(address);
result = _spi_read();
CS_on;
return(result);
}
// ppm input interrupt
void read_ppm()
{
#if F_CPU == 16000000
#define PPM_SCALE 1L
#elif F_CPU == 8000000
#define PPM_SCALE 0L
#else
#error // 8 or 16MHz only !
#endif
static unsigned int pulse;
static unsigned long counterPPM;
static byte chan;
counterPPM = TCNT1;
TCNT1 = 0;
if(counterPPM < 510 << PPM_SCALE) { //must be a pulse if less than 510us
pulse = counterPPM;
}
else if(counterPPM > 1910 << PPM_SCALE) { //sync pulses over 1910us
chan = 0;
}
else{ //servo values between 510us and 2420us will end up here
if(chan < CHANNELS) {
Servo_data[chan]= constrain((counterPPM + pulse) >> PPM_SCALE, PPM_MIN, PPM_MAX);
}
chan++;
}
}
@mareksuma1985
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mareksuma1985 commented Feb 1, 2026

How should I change this code to make it RX?

nrf24_cx10.c

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