nRF51822_BLE.c

#include <stdint.h>
#include <nrf.h>
#include "rtc.h"

/* 参考：
	- http://blog.chinaunix.net/uid-28852942-id-5745469.html
		- サンプルプログラム。中国の方。
	- https://pe-bank.jp/guide/column/theme/iot_things/20170919
	- https://pe-bank.jp/guide/column/theme/iot_things/20171120
		- この2つはパケットの基本構造についてざっくり理解するのに必要。
	- https://sites.google.com/a/gclue.jp/ble-docs/advertising-1/advertising
		- iPhoneから送出されるパケットをビット単位で説明してくれている。
	- https://fabo.gitbooks.io/bledocs/content/nordic/beaconadvparam.html
	- https://fabo.gitbooks.io/bledocs/content/nordic/beaconadvdata.html
		- 上2つはアドバタイズのパラメータについて。
	- https://devzone.nordicsemi.com/f/nordic-q-a/11640/nrf51822-raw-transmit-receive-not-working
		- 「RADIO実行中はずっとHFCLK(外部クリスタルとして)を起動しておかないと」と示唆。
	- https://qiita.com/hktechno/items/f594f87493fbe11de3fb
		- UICRを書き換えなければならないという事をここで知る。
*/
static uint8_t packetBuffer[64];
#define BLE_ADV_ADDRESS 0x8E89BED6
void radio_ble_init(void) {
	NRF_RADIO->MODE = 3; // BLE mode
	NRF_RADIO->TXPOWER = 4; // +4dBm
	NRF_RADIO->FREQUENCY = 2; // Ch 37 for Advertising

	// Packet Format Decision
	NRF_RADIO->PCNF0 = (1 << 8) | (8 << 0); // 1byte S0, 8bit Length
	NRF_RADIO->PCNF1 = (37 << 0) | ((4-1) << 16); // max 31bytes payload, 4bytes address

	NRF_RADIO->CRCCNF = 3 | (1 << 8);
	NRF_RADIO->CRCPOLY = (1 << 24) | (1 << 10) | (1 << 9) | (1 << 6) | (1 << 4) | (1 << 3) | (1 << 1) | (1 << 0);
	NRF_RADIO->CRCINIT = 0x555555;

	// Address
	NRF_RADIO->BASE0 = BLE_ADV_ADDRESS << 8;
	NRF_RADIO->PREFIX0 = BLE_ADV_ADDRESS >> 24;

	NRF_RADIO->PCNF1 |= (1 << 25);
	NRF_RADIO->DATAWHITEIV = 0x25;

	NRF_RADIO->OVERRIDE4 = 1 << 31;
	NRF_RADIO->OVERRIDE0 = NRF_FICR->BLE_1MBIT[0];
	NRF_RADIO->OVERRIDE1 = NRF_FICR->BLE_1MBIT[1];
	NRF_RADIO->OVERRIDE2 = NRF_FICR->BLE_1MBIT[2];
	NRF_RADIO->OVERRIDE3 = NRF_FICR->BLE_1MBIT[3];
	NRF_RADIO->OVERRIDE4 = NRF_FICR->BLE_1MBIT[4];
}

void radio_memwrite_adv_data(void) {
	// == PDU Header ==
	packetBuffer[0] = 0x42; // ADV_NONCONN_IND
	packetBuffer[1] = 6 + 3 + 5; // Length。アドレス分も長さが要るっぽい？
	// ===== AdvA =====
	packetBuffer[2] = 0x93;
	packetBuffer[3] = 0x08;
	packetBuffer[4] = 0x81;
	packetBuffer[5] = 0x14;
	packetBuffer[6] = 0x45;
	packetBuffer[7] = 0x11;
	// ===== AdvData =====
	// -- Data0 ---
	packetBuffer[8] = 2; // Length
	packetBuffer[9] = 0x01; // flag
	packetBuffer[10] = 0x06; // General & Discoverable, Only for BLE
	// --- Data1 ---
	packetBuffer[11] = 4; // Length
	packetBuffer[12] = 0x09; // Complete Local Name
	packetBuffer[13] = 'n';
	packetBuffer[14] = 'R';
	packetBuffer[15] = 'F';
}

void radio_tx(void) {
	NRF_RADIO->PACKETPTR = (uintptr_t)packetBuffer;
	radio_memwrite_adv_data();
	NRF_RADIO->TXADDRESS = 0;

	NRF_RADIO->TASKS_TXEN = 1;
	while( !NRF_RADIO->EVENTS_READY );
	NRF_RADIO->EVENTS_READY = 0;

	NRF_RADIO->TASKS_START = 1;

	while( !NRF_RADIO->EVENTS_END );
	NRF_RADIO->EVENTS_END = 0;

	NRF_RADIO->TASKS_DISABLE = 1;
	while( !NRF_RADIO->EVENTS_DISABLED );
	NRF_RADIO->EVENTS_DISABLED = 0;
}

static uint8_t rxBuffer[32];
void radio_rx(void) {
	NRF_RADIO->PACKETPTR = (uintptr_t)rxBuffer;
	NRF_RADIO->RXADDRESSES = 1; // Enable RX for Address 0

	NRF_RADIO->TASKS_RXEN = 1;
	while( !NRF_RADIO->EVENTS_READY );
	NRF_RADIO->EVENTS_READY = 0;

	NRF_RADIO->TASKS_START = 1;

	while( !NRF_RADIO->EVENTS_END );
	NRF_RADIO->EVENTS_END = 0;

	NRF_RADIO->TASKS_DISABLE = 1;
	while( !NRF_RADIO->EVENTS_DISABLED );
	NRF_RADIO->EVENTS_DISABLED = 0;
}

int main(void) {
	rtc_init();
	radio_ble_init();

	while(1) {
		radio_tx();
		radio_rx();
		ms_wait(100);
	}
}