wayne roberts
point-2-point demo
radio chip selection
Radio chip driver is not included, because these options are available.
If you're using SX1272 or SX1276, then import sx127x driver into your program.
if you're using SX1261 or SX1262, then import sx126x driver into your program.
if you're using SX1280, then import sx1280 driver into your program.
If you're using NAmote72 or Murata discovery, then you must import only sx127x driver.
TX trigger selection
Edit main.h to define DIGITAL_TRIGGER or ANALOG_TRIGGER to chose whether transmit is initiated by digital pin (button/jumper) or analog pin(s) level change.
This project is intended to be used on two LoRa shields.
Each board sits in continuous RX mode, waiting for request packet.
If the received packet has good CRC, the packet is acknowledged along with read of ADC sample from the replying device.
The original request packet also contains instruction to set level of output pin.
Both sides of the link are running the same code, and each can initiate a transmission at any time.
No addressing is used, so only two nodes can operate on the radio channel.
Diff: main.cpp
- Revision:
- 0:1d8d218c5cc5
- Child:
- 1:d95d135a4fb4
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp Thu Oct 05 16:11:31 2017 -0700
@@ -0,0 +1,239 @@
+#include "sx127x_lora.h"
+
+DigitalOut myled(LED1);
+
+SPI spi(D11, D12, D13); // mosi, miso, sclk
+// dio0, dio1, nss, spi, rst
+SX127x radio( D2, D3, D10, spi, A0); // sx1276 arduino shield
+
+SX127x_lora lora(radio);
+DigitalInOut rfsw(A4); // for SX1276 arduino shield
+
+InterruptIn user_button(USER_BUTTON);
+Timer t;
+Ticker ticker;
+AnalogIn a1(A1);
+DigitalOut pc6_out(PC_6);
+
+DigitalOut jumper_out(PC_10);
+InterruptIn jumper_in(PC_12);
+
+void rfsw_callback()
+{
+ if (radio.RegOpMode.bits.Mode == RF_OPMODE_TRANSMITTER)
+ rfsw = 1;
+ else
+ rfsw = 0;
+}
+
+/**********************************************************************/
+#define CMD_OUT_PIN 0x01
+#define CMD_OUT_PIN_ACK (CMD_OUT_PIN | 0x80)
+
+uint8_t out_pin_state;
+
+
+static uint16_t crc16( uint8_t *buffer, uint16_t length )
+{
+ uint16_t i;
+ // The CRC calculation follows CCITT
+ const uint16_t polynom = 0x1021;
+ // CRC initial value
+ uint16_t crc = 0x0000;
+
+ if( buffer == NULL )
+ {
+ return 0;
+ }
+
+ for( i = 0; i < length; ++i )
+ {
+ uint16_t j;
+ crc ^= ( uint16_t ) buffer[i] << 8;
+ for( j = 0; j < 8; ++j )
+ {
+ crc = ( crc & 0x8000 ) ? ( crc << 1 ) ^ polynom : ( crc << 1 );
+ }
+ }
+
+ return crc;
+}
+
+void tx_ack()
+{
+ uint8_t n = 0;
+ uint16_t crc;
+
+ if (radio.rx_buf[0] == CMD_OUT_PIN) {
+ uint16_t ain = a1.read_u16();
+ radio.tx_buf[n++] = CMD_OUT_PIN_ACK;
+ /* TODO read analog pin and digital input pin */
+ radio.tx_buf[n++] = ain;
+ radio.tx_buf[n++] = ain >> 8;
+ } else
+ radio.tx_buf[n++] = 0xff;
+
+ crc = crc16(radio.tx_buf, n);
+ radio.tx_buf[n++] = crc;
+ radio.tx_buf[n++] = crc >> 8;
+
+ lora.RegPayloadLength = n;
+ radio.write_reg(REG_LR_PAYLOADLENGTH, lora.RegPayloadLength);
+
+ lora.start_tx(lora.RegPayloadLength); /* begin transmission */
+
+ printf("tx-ack-start\r\n");
+ while (lora.service() != SERVICE_TX_DONE) /* wait for transmission to complete */
+ ;
+
+ lora.start_rx(RF_OPMODE_RECEIVER);
+ printf("tx-ack-end\r\n");
+}
+
+void tx()
+{
+ int i;
+
+ for (i = 0; i < 3; i++) {
+ uint8_t n = 0;
+ uint16_t crc;
+ int rx_timeout_at;
+
+ radio.tx_buf[n++] = CMD_OUT_PIN;
+ radio.tx_buf[n++] = out_pin_state;
+ crc = crc16(radio.tx_buf, n);
+ radio.tx_buf[n++] = crc;
+ radio.tx_buf[n++] = crc >> 8;
+
+ lora.RegPayloadLength = n;
+ radio.write_reg(REG_LR_PAYLOADLENGTH, lora.RegPayloadLength);
+
+ lora.start_tx(lora.RegPayloadLength); /* begin transmission */
+
+ while (lora.service() != SERVICE_TX_DONE) /* wait for transmission to complete */
+ ;
+ rx_timeout_at = t.read_us() + 200000;
+
+ lora.start_rx(RF_OPMODE_RECEIVER);
+
+ while (t.read_us() < rx_timeout_at) {
+ if (lora.service() == SERVICE_READ_FIFO) {
+ uint16_t rx_crc;
+ rx_crc = radio.rx_buf[lora.RegRxNbBytes-2];
+ rx_crc |= radio.rx_buf[lora.RegRxNbBytes-1] << 8;
+ crc = crc16(radio.rx_buf, lora.RegRxNbBytes-2);
+ if (crc == rx_crc) {
+ printf("crcOk %u\r\n", i);
+ if (radio.rx_buf[0] == CMD_OUT_PIN_ACK) {
+ uint16_t ain = radio.rx_buf[0];
+ ain |= radio.rx_buf[1] << 8;
+ printf("ain %u\r\n", ain);
+ }
+ return;
+ } else
+ printf("crcFail %04x != %04x\r\n", crc, rx_crc);
+ }
+ }
+ printf("rx-timeout %u\r\n", i);
+ } // ..for()
+}
+
+volatile bool start_tx;
+
+void button_isr()
+{
+ if (!jumper_in.read())
+ start_tx = true;
+}
+
+void auto_tx()
+{
+ if (jumper_in.read())
+ start_tx = true;
+ else
+ ticker.detach();
+}
+
+int main()
+{
+ bool jin = false;
+ printf("\r\nreset\r\n");
+
+ jumper_out = 1;
+ jumper_in.mode(PullDown);
+
+ while (!user_button) {
+ printf("button-lo\r\n");
+ wait(0.01);
+ }
+ user_button.fall(&button_isr);
+ t.start();
+
+ radio.rf_switch = rfsw_callback;
+
+ radio.set_frf_MHz(917.3);
+ lora.enable();
+ lora.setBw_KHz(500);
+ lora.setSf(9);
+
+ /* RFO or PABOOST choice:
+ * SX1276 shield: RFO if using 900MHz, or PA_BOOST if using 433MHz
+ */
+ rfsw.input();
+ if (rfsw.read()) {
+ printf("LAS\r\n");
+ /* LAS HF=PA_BOOST LF=RFO */
+ if (radio.HF)
+ radio.RegPaConfig.bits.PaSelect = 1;
+ else
+ radio.RegPaConfig.bits.PaSelect = 0;
+ } else {
+ /* MAS shield board, only RFO TX */
+ radio.RegPaConfig.bits.PaSelect = 0;
+ printf("MAS\r\n");
+ }
+ rfsw.output();
+ radio.write_reg(REG_PACONFIG, radio.RegPaConfig.octet);
+
+ lora.start_rx(RF_OPMODE_RECEIVER);
+
+ for (;;) {
+
+ if (jumper_in.read()) {
+ if (!jin) {
+ ticker.attach(auto_tx, 0.5);
+ jin = true;
+ }
+ } else {
+ jin = false;
+ }
+
+ if (start_tx) {
+ out_pin_state ^= 1;
+ tx();
+ start_tx = false;
+ }
+ if (lora.service() == SERVICE_READ_FIFO) {
+ uint16_t crc, rx_crc;
+ int i;
+ for (i = 0; i < lora.RegRxNbBytes; i++) {
+ printf("%02x ", radio.rx_buf[i]);
+ }
+ printf("\r\n");
+ rx_crc = radio.rx_buf[lora.RegRxNbBytes-2];
+ rx_crc |= radio.rx_buf[lora.RegRxNbBytes-1] << 8;
+ crc = crc16(radio.rx_buf, lora.RegRxNbBytes-2);
+ if (crc == rx_crc) {
+ printf("crcOk\r\n");
+ if (radio.rx_buf[0] == CMD_OUT_PIN) {
+ pc6_out.write(radio.rx_buf[1]);
+ printf("out pin state: %u", radio.rx_buf[1]);
+ }
+ printf("\r\n");
+ tx_ack();
+ } else
+ printf("crc %04x != %04x\r\n", crc, rx_crc);
+ } // ..if something received
+ } // ..for (;;)
+}
+