added nrf52 rf ring index

69c3bb52 · Sam Calisch · 4bd51afe · 69c3bb52
Commit 69c3bb52 authored 7 years ago by Sam Calisch
--- a/rf/nrf52832/index.html
+++ b/rf/nrf52832/index.html
+<html>
+<head>
+<style>
+pre code {
+  background-color: #eee;
+  border: 1px solid #999;
+  display: block;
+  padding: 20px;
+}
+figure{
+  text-align: center
+}
+</style>
+
+
+</head>
+<body>
+
+<h1>NRF52832</h1>
+
+<figure>
+<img src='nrf52-rf-ring-2.png' width=50%>
+<figcaption>RF Ring oscillator with nrf52.</figcaption>
+</figure>
+
+<p>This RF ring oscillator runs on the NRF52 BLE SOC using the Adafruit feather development board.  The NRF52 has an ARM Cortex M4F running at 64 MHz with built in BLE radio.  An arduino sketch for the oscillator is available <a href='nrf52-rf-ring.ino'>here</a>, or visible below.</p>
+
+<pre>
+<code>
+#define toggle_mask 1<<7 //this is for the scope
+
+static uint8_t packet = 12; //declare a buffer for our packet to use with easydma
+
+void wait_for_end(){
+  while(!(NRF_RADIO->EVENTS_END)){}
+  NRF_RADIO->EVENTS_END = 0; //clear end event  
+}
+void wait_for_ready(){
+  while(!(NRF_RADIO->EVENTS_READY)){} 
+  NRF_RADIO->EVENTS_READY = 0; //clear ready event
+}
+void disable_radio(){
+  NRF_RADIO->EVENTS_DISABLED = 0; //clear disabled event
+  NRF_RADIO->TASKS_DISABLE = 1;
+  while(!(NRF_RADIO->EVENTS_DISABLED)){} 
+}
+
+void send_token(){
+  NRF_GPIO->OUTSET = toggle_mask; //set toggle pin high  
+  NRF_RADIO->EVENTS_READY = 0; //clear ready event
+  NRF_RADIO->TASKS_TXEN=1; //trigger tx enable task
+  delayMicroseconds(15);
+  //wait_for_ready(); //since we're switching, maybe we can get around this?
+  NRF_RADIO->TASKS_START=1;  //start
+  wait_for_end();
+  NRF_GPIO->OUTCLR = toggle_mask; //set toggle pin low
+
+  //put radio in RX mode
+  NRF_RADIO->EVENTS_READY = 0; //clear ready event
+  NRF_RADIO->TASKS_RXEN=1; //trigger rx enable task
+  wait_for_ready();  
+  NRF_RADIO->TASKS_START=1;
+}
+
+void setup() {
+  //helpful bitmasks in nrf52_bitfields.h
+  //Serial.begin(115200);  //for debug only
+  NRF_GPIO->DIRSET = toggle_mask; //set toggling pin to output
+
+  NRF_RADIO->POWER = RADIO_POWER_POWER_Disabled; //turn off radio to reset registers
+  delay(10);
+  NRF_RADIO->POWER = RADIO_POWER_POWER_Enabled; //turn on radio
+  delay(10);
+
+  // Radio config
+  NRF_RADIO->TXPOWER   = (RADIO_TXPOWER_TXPOWER_Pos3dBm << RADIO_TXPOWER_TXPOWER_Pos);
+  NRF_RADIO->FREQUENCY = 7UL;  // Frequency bin 7, 2407MHz
+  NRF_RADIO->MODE      = (RADIO_MODE_MODE_Nrf_2Mbit << RADIO_MODE_MODE_Pos);
+
+  NRF_RADIO->PREFIX0 = ((uint32_t)0xC0 << 0); // Prefix byte of address 0
+  NRF_RADIO->BASE0 = 0x01234567UL;  // Base address for prefix 0
+  NRF_RADIO->TXADDRESS   = 0x00UL;  // Set device address 0 to use when transmitting
+  NRF_RADIO->RXADDRESSES = 0x01UL;  // Enable device address 0 to use to select which addresses to receive
+
+  // Packet configuration
+  NRF_RADIO->PCNF0 = (0 << RADIO_PCNF0_S1LEN_Pos) | (0 << RADIO_PCNF0_S0LEN_Pos) | (0 << RADIO_PCNF0_LFLEN_Pos); 
+  NRF_RADIO->PCNF1 = (RADIO_PCNF1_WHITEEN_Disabled << RADIO_PCNF1_WHITEEN_Pos) |
+                     (RADIO_PCNF1_ENDIAN_Big       << RADIO_PCNF1_ENDIAN_Pos)  |
+                     (2 << RADIO_PCNF1_BALEN_Pos);
+
+  // CRC Config
+  NRF_RADIO->CRCCNF = (RADIO_CRCCNF_LEN_Disabled << RADIO_CRCCNF_LEN_Pos); // Number of checksum bits
+  //NRF_RADIO->CRCINIT = 0xFFFFUL;   // Initial value
+  //NRF_RADIO->CRCPOLY = 0x11021UL;  // CRC poly: x^16 + x^12^x^5 + 1
+
+  NRF_RADIO->MODECNF0 |= RADIO_MODECNF0_RU_Fast << RADIO_MODECNF0_RU_Pos; //turn on fast ramp up
+  NRF_RADIO->SHORTS = 0; //turn off all shortcuts, for debug
+    
+  //packet
+  NRF_RADIO->PACKETPTR = (uint32_t)&packet; //set pointer to packet buffer
+
+  //start HFCLK
+  NRF_CLOCK->TASKS_HFCLKSTART = 1;
+  while(!(NRF_CLOCK->HFCLKSTAT & CLOCK_HFCLKSTAT_STATE_Msk)){} //wait for hfclk to start
+  delay(10);
+  
+  send_token(); //send a starting token
+  while(1){   
+    if ( NRF_RADIO->EVENTS_END ){
+      NRF_RADIO->EVENTS_END = 0; //clear end event
+      packet += 1; //increment for fun
+      send_token();
+    }
+    //delay(100);
+    //Serial.println(packet);  //for debug only
+  }
+}
+ 
+void loop() {}
+</code>
+</pre>
+
+<p>Note: This test was run on a the Adafruit Feather Dev board, which uses the Raytac MDBT42Q module, incorporating the NRF52.  The module retails for $7, the development board retails $24.  Other modules are available for $5 from Fanstel.</p>
+
+
+<figure>
+<img src='radio-modes.png' width=80%>
+<img src='radio-timing.png' width=60%>
+<figcaption>A) NRF52 Radio Modes. B) Timing</figcaption>
+</figure>
+
+
+
+
+<p><a href='../index.html'>Back</a></p>
+
+</body>
+
+</html>
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