OpenPuck/ReversePuckFirmware/radio.cpp

#include "radio.h"

// *** VERBATIM COPY of OpenPuck/radio.cpp -- keep byte-identical (see radio.h header note). ***
// On the controller emulator rfGenSessionAddr() only seeds a safe default; the operational session
// address is ADOPTED from the puck's E1 host frame in ctrl_link.cpp.

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: clean channel in the real puck's active hop set {18,2,80}. Tunable.
uint8_t g_sessCh = 18;

// Safe default; adopted from the puck's E1 host frame at connect time.
uint8_t g_sessBase[4] = { 0x69, 0x62, 0x65, 0x78 };
uint8_t g_sessPrefix = 0x10;

void rfGenSessionAddr()
{
	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;
}

uint8_t rfrx[100], rftx[100];
uint32_t g_rfRxCount = 0;

// Puck-link config decoded from real-puck capture: Ble_2Mbit, ENDIAN=Big, NO whitening, addr "ibex",
// CRC16 0x11021/0xFFFF; static-length frame.
uint32_t g_crcinit = 0xFFFF;
uint8_t g_whiteiv = 37;
uint8_t g_mode = RADIO_MODE_MODE_Ble_2Mbit;

// S0LEN0, LFLEN8, S1LEN3 (ESB DPL) - CRC-VALIDATED
uint32_t g_pcnf0 = 0x00030008UL;
uint8_t g_statlen = 0x20;

// ENDIAN=Big, BALEN4, MAXLEN=96.
uint32_t g_pcnf1 = 0x01040060;
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);
	NRF_RADIO->FREQUENCY = ch;
	// +8dBm = the nRF52840's max TX power (was 0dBm). Mirrors OpenPuck/radio.cpp: the link margin is thin on
	// the Pro Micro's PCB-trace antenna (RSSI ~20dB below a real Valve unit) and 2.4GHz is crowded, so our F1
	// replies at 0dBm were being missed by the puck -> the reply gaps that read as intermittent disconnects
	// (and, past the puck's RF_STALL_MS, trip its radio power-cycle self-heal = churn). The puck already
	// transmits its polls/beacons at +8dBm; matching it on our reply side closes the asymmetry. USB-powered,
	// so the higher current draw is free.
	NRF_RADIO->TXPOWER =
		(RADIO_TXPOWER_TXPOWER_Pos8dBm << 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;

	NRF_RADIO->PCNF1 =
		g_pcnf1 ? g_pcnf1 :
			  ((1u << RADIO_PCNF1_ENDIAN_Pos) |
			   ((uint32_t)g_balen << RADIO_PCNF1_BALEN_Pos) |
			   ((uint32_t)g_statlen << RADIO_PCNF1_STATLEN_Pos) |
			   ((uint32_t)g_statlen << RADIO_PCNF1_MAXLEN_Pos));
	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;
}