OpenPuck/OpenPuck/radio.cpp

#include "radio.h"

// Pairing rendezvous bytes from IBEX rodata. The 0x91A2A793 key that precedes the "ibex" string is a
// DIFFERENT key, NOT the discovery address (confirmed via PTR_s_ibexesb_common=0x56f99 -> "ibex...").
const uint8_t PAIR_BASE[4] = {0x69, 0x62, 0x65, 0x78};  // "ibex"
uint8_t  g_rfPrefix = 0x10;
uint8_t  g_rfCh = 2;
uint8_t  g_rfBase[4] = {0x69, 0x62, 0x65, 0x78};  // "ibex"
// ch18 measured clean (RSSI 95/90, PER 0) on the REAL PUCK's own channel scan and is in its active hop set
// {18,2,80}; trackpad data bursts collide on bad channels -> reply-rate crash. Tunable 'C'.
uint8_t  g_sessCh = 18;

// pre-init to "ibex"/0x10 as a safe default; rfGenSessionAddr() overwrites with the per-device value at boot.
uint8_t  g_sessBase[4] = {0x69, 0x62, 0x65, 0x78};
uint8_t  g_sessPrefix = 0x10;

void rfGenSessionAddr(){
  // Mix the 64-bit FICR DEVICEID into a 4-byte base + a prefix. Deterministic per chip (stable across reboots,
  // debuggable) and unique across chips (DEVICEID is unique) -> two OpenPucks never collide on the connected
  // session. Avoid degenerate address bytes (0x00/0xFF) for clean preamble correlation, and never reproduce
  // the shared discovery base "ibex" (else the isolation is lost).
  uint32_t h  = NRF_FICR->DEVICEID[0] * 0x9E3779B1u ^ NRF_FICR->DEVICEID[1];
  uint32_t h2 = NRF_FICR->DEVICEID[1] * 0x85EBCA6Bu ^ NRF_FICR->DEVICEID[0];
  for(int i=0;i<4;i++){ uint8_t b=(uint8_t)(h>>(i*8)); if(b==0x00||b==0xFF) b^=0x5A; g_sessBase[i]=b; }
  uint8_t p=(uint8_t)(h2>>16); if(p==0x00||p==0xFF) p=0x5C; g_sessPrefix=p;
  if(g_sessBase[0]==g_rfBase[0] && g_sessBase[1]==g_rfBase[1] &&
     g_sessBase[2]==g_rfBase[2] && g_sessBase[3]==g_rfBase[3]) g_sessBase[0]^=0x80;   // collided with "ibex"
}

uint8_t  rfrx[80], rftx[80];
uint32_t g_rfRxCount = 0;

// HYBRID puck-link config (firmware-derived, definitive). DECODED from real-puck capture: puck TX = Ble_2Mbit,
// ENDIAN=Big (MSB-first), NO whitening, addr "ibex", CRC16 0x11021/0xFFFF; frame = FUN_00027e9a (static length).
uint32_t g_crcinit = 0xFFFF;
uint8_t  g_whiteiv = 37;
uint8_t  g_mode    = RADIO_MODE_MODE_Ble_2Mbit;   // <-- was the bug (1Mbit). Real puck = 2Mbit.
uint32_t g_pcnf0   = 0x00030008UL;                // S0LEN0, LFLEN8, S1LEN3 (ESB DPL) - CRC-VALIDATED
uint8_t  g_statlen = 0x20;
uint32_t g_pcnf1   = 0x01040040;                  // ENDIAN=Big, BALEN4, MAXLEN64 - CRC-VALIDATED
uint32_t g_crcpoly = 0x11021UL;
uint16_t g_crccnf  = 0x2;                          // CRC16, address included
uint8_t  g_pid     = 0;
uint8_t  g_balen   = 4;                            // ESB 5-byte addr
bool     g_prefixRaw = false;

uint8_t rfBitrev8(uint8_t x){ uint8_t y=0; for(int i=0;i<8;i++){y=(y<<1)|(x&1);x>>=1;} return y; }

void rfSetAddr(const uint8_t b4[4], uint8_t prefix){
  uint8_t b[4]; for(int i=0;i<4;i++) b[i]=rfBitrev8(b4[i]);
  NRF_RADIO->BASE0   = ((uint32_t)b[0]<<24)|((uint32_t)b[1]<<16)|((uint32_t)b[2]<<8)|b[3];
  NRF_RADIO->PREFIX0 = g_prefixRaw ? prefix : rfBitrev8(prefix);
  NRF_RADIO->TXADDRESS = 0; NRF_RADIO->RXADDRESSES = 1u<<0;
}

void rfConfig(uint8_t ch){
  NRF_RADIO->TASKS_DISABLE = 1; RWAIT_DISABLED(); NRF_RADIO->EVENTS_DISABLED = 0;
  NRF_RADIO->MODE = ((uint32_t)g_mode << RADIO_MODE_MODE_Pos);   // Ble_2Mbit (tunable 'M')
  NRF_RADIO->FREQUENCY = ch;
  NRF_RADIO->TXPOWER   = (RADIO_TXPOWER_TXPOWER_0dBm << RADIO_TXPOWER_TXPOWER_Pos);
#if defined(RADIO_MODECNF0_RU_Fast)
  NRF_RADIO->MODECNF0 = (RADIO_MODECNF0_RU_Fast<<RADIO_MODECNF0_RU_Pos);
#endif
  NRF_RADIO->PCNF0 = g_pcnf0;       // static length (tunable '0'); g_pcnf1=0 -> build from g_statlen/g_balen
  NRF_RADIO->PCNF1 = g_pcnf1 ? g_pcnf1 :
        ((1u<<RADIO_PCNF1_ENDIAN_Pos)              // ENDIAN=Big (puck transmits MSB-first)
        |((uint32_t)g_balen<<RADIO_PCNF1_BALEN_Pos)
        |((uint32_t)g_statlen<<RADIO_PCNF1_STATLEN_Pos)
        |((uint32_t)g_statlen<<RADIO_PCNF1_MAXLEN_Pos));   // WHITEEN=0
  NRF_RADIO->CRCCNF = g_crccnf;     // CRC16, address included
  NRF_RADIO->CRCPOLY = g_crcpoly; NRF_RADIO->CRCINIT = g_crcinit;
  NRF_RADIO->DATAWHITEIV = g_whiteiv;
  NRF_RADIO->PACKETPTR = (uint32_t)rfrx;
}