working on radio link for stage, moved code from step project

as5013-test/nrf52-as5013/host.py

+#!/usr/bin/env python
+import numpy as np
+from math import *
+import serial, time
+import struct
+import sys
+import socket
+import matplotlib.pyplot as plt
+import matplotlib.animation as animation
+import bitstring
+
+n_samples = 20
+
+def read_as5013_12bit(bytes):
+	return (bitstring.Bits(bytes=bytes, length=16)<<4).unpack('uint:16')[0]
+	#signed 12 bit val comes in two bytes
+	#return struct.unpack("<h",bytearray([ (high<<4) , low<<4 ]))[0]
+
+def read(ser=None):
+	if ser is None:
+		print "No serial connection!"
+	else:
+		c = ser.read(n_samples)
+		data = [read_as5013_12bit(c[x:x+2]) for x in xrange(0,n_samples,2)]
+		return data
+
+def main():
+	try:
+		ser = serial.Serial(port='/dev/tty.usbserial-FT9L3KWR',baudrate=1000000,timeout=1.)
+		ser.isOpen()
+		print "Established serial connection."
+	except(OSError):
+		#no serial port
+		print "Couldn't find the serial port, entering debug mode."
+		ser = None
+	ser.flush()
+
+
+	while True: 
+		#connection, address = serversocket.accept()
+
+		try:
+			data = np.asarray(read(ser=ser))
+			print data[1::2] - data[::2]
+		except(KeyboardInterrupt):
+			break
+		#if data:
+		#	clientsocket.send(data)
+	print "quitting"
+	ser.close()
+
+
+
+if __name__ == '__main__':
+	main()

as5013-test/nrf52-as5013/nrf52-as5013.ino

-//read raw values from as5013 hall effect array ic
+//read raw values from as5013 hall effect array ic and pass to uarte
 //sec, 2017
+#include "radio.h"
 
 //as5013 registers
 #define ctrl_reg 0x0F
+#define y_res_reg 0x11
 #define T_ctrl_reg 0x2D
 #define c_raw_values_start 0x16 //starting address for raw sensor values
 #define n_tx_bytes 1 //only need transmit the start read address
@@ -11,27 +13,39 @@
 #define scl_pin 0 //XL1
 #define sda_pin 1 //XL2
 #define rst_pin 3 //A1
-
 static uint8_t txdata[n_tx_bytes] = {0};
 static uint8_t rxdata[n_rx_bytes] = {0};
 
-//raw sensor values
-volatile int16_t c1,c2,c3,c4,c5;
+//uarte
+const uint8_t pin_rx = 8;
+const uint8_t pin_tx = 6;
+uint16_t last_tx_time = 0;
+uint16_t tx_period = 100; //ms
 
-void twi_tx(){
-  // triggering the STARTTX task
-  NRF_TWIM0->TASKS_STARTTX = 1;
-  while( !(NRF_TWIM0->EVENTS_STOPPED) ){}
-}
-void twi_rx(){
-  // triggering the STARTRX task
-  NRF_TWIM0->TASKS_STARTRX = 1;
-  while( !(NRF_TWIM0->EVENTS_STOPPED) ){}
+//
+//UARTE
+//
+void uarte_setup(){
+  //uart with dma
+  NRF_UARTE0->PSEL.TXD = (pin_tx << UARTE_PSEL_TXD_PIN_Pos) & UARTE_PSEL_TXD_PIN_Msk;
+  NRF_UARTE0->PSEL.RXD = (pin_rx << UARTE_PSEL_RXD_PIN_Pos) & UARTE_PSEL_RXD_PIN_Msk;
+  NRF_UARTE0->CONFIG =  ((UART_CONFIG_PARITY_Excluded << UARTE_CONFIG_PARITY_Pos) & UARTE_CONFIG_PARITY_Msk) 
+                      | ((UARTE_CONFIG_HWFC_Disabled << UARTE_CONFIG_HWFC_Pos) & UARTE_CONFIG_HWFC_Msk);
+  NRF_UARTE0->BAUDRATE = UART_BAUDRATE_BAUDRATE_Baud1M;
+  NRF_UARTE0->ENABLE = (UARTE_ENABLE_ENABLE_Enabled << UARTE_ENABLE_ENABLE_Pos) & UARTE_ENABLE_ENABLE_Msk;
+  
+  NRF_UARTE0->TXD.MAXCNT = n_rx_bytes;
 }
 
-void setup() {
-  Serial.begin(115200);
 
+//
+//TWI
+//
+void twi_set_cnts(uint8_t n_tx, uint8_t n_rx){
+  NRF_TWIM0->TXD.MAXCNT = (n_tx << TWIM_TXD_MAXCNT_MAXCNT_Pos) & TWIM_TXD_MAXCNT_MAXCNT_Msk;
+  NRF_TWIM0->RXD.MAXCNT = (n_rx << TWIM_RXD_MAXCNT_MAXCNT_Pos) & TWIM_RXD_MAXCNT_MAXCNT_Msk;  
+}
+void twi_setup(){
   //Need to switch to internal LFCLK to disconnect from XL1 and XL2
   NRF_CLOCK->LFCLKSRC = 0; //disconnect XL1 AND XL2 FROM LFCLK?
   NRF_CLOCK->EVENTS_LFCLKSTARTED = 0;
@@ -42,12 +56,6 @@ void setup() {
   NRF_GPIO->PIN_CNF[scl_pin] = (GPIO_PIN_CNF_DRIVE_S0D1 << GPIO_PIN_CNF_DRIVE_Pos) & GPIO_PIN_CNF_DRIVE_Msk;
   NRF_GPIO->PIN_CNF[sda_pin] = (GPIO_PIN_CNF_DRIVE_S0D1 << GPIO_PIN_CNF_DRIVE_Pos) & GPIO_PIN_CNF_DRIVE_Msk;
   NRF_GPIO->DIRCLR = (1<<scl_pin)|(1<<sda_pin); //set SDA/SCL as inputs (likely not necessary)
-  
-  NRF_GPIO->DIRSET = (1<<rst_pin); //set AS5013 nRESET pin as output
-  NRF_GPIO->OUTCLR = (1<<rst_pin); //hardware reset
-  delay(1);
-  NRF_GPIO->OUTSET = (1<<rst_pin); //turn on as5013
-  delay(1);
 
   NRF_TWIM0->PSEL.SCL = ((scl_pin << TWIM_PSEL_SCL_PIN_Pos) & TWIM_PSEL_SCL_PIN_Msk)
                       | ((TWIM_PSEL_SCL_CONNECT_Connected << TWIM_PSEL_SCL_CONNECT_Pos) & TWIM_PSEL_SCL_CONNECT_Msk);
@@ -57,37 +65,85 @@ void setup() {
   NRF_TWIM0->ADDRESS = (0x41 << TWI_ADDRESS_ADDRESS_Pos) & TWI_ADDRESS_ADDRESS_Msk;
   NRF_TWIM0->TXD.PTR = (uint32_t)(&txdata);
   NRF_TWIM0->RXD.PTR = (uint32_t)(&rxdata);
-  NRF_TWIM0->TXD.MAXCNT = (n_tx_bytes << TWIM_TXD_MAXCNT_MAXCNT_Pos) & TWIM_TXD_MAXCNT_MAXCNT_Msk;
-  NRF_TWIM0->RXD.MAXCNT = (n_rx_bytes << TWIM_RXD_MAXCNT_MAXCNT_Pos) & TWIM_RXD_MAXCNT_MAXCNT_Msk;
+  twi_set_cnts(n_tx_bytes, n_rx_bytes);
   //set up short between LASTTX and STOP and between LASTRX and STOP
   NRF_TWIM0->SHORTS = ((TWIM_SHORTS_LASTTX_STOP_Enabled << TWIM_SHORTS_LASTTX_STOP_Pos) & TWIM_SHORTS_LASTTX_STOP_Msk)
                     | ((TWIM_SHORTS_LASTRX_STOP_Enabled << TWIM_SHORTS_LASTRX_STOP_Pos) & TWIM_SHORTS_LASTRX_STOP_Msk);
   //NRF_TWIM0->ENABLE = (TWI_ENABLE_ENABLE_Enabled << TWI_ENABLE_ENABLE_Pos) & TWI_ENABLE_ENABLE_Msk;
   //There's a typo in nrf52_bitfields, so we set this manually.
   NRF_TWIM0->ENABLE = (6 << TWI_ENABLE_ENABLE_Pos) & TWI_ENABLE_ENABLE_Msk;
-  
+}
+void twi_tx(){
+  // clear the stopped event
+  NRF_TWIM0->EVENTS_STOPPED = 0;
+  // triggering the STARTTX task
+  NRF_TWIM0->TASKS_STARTTX = 1;
+  while( !(NRF_TWIM0->EVENTS_STOPPED) ){}
+}
+void twi_rx(){
+  // clear the stopped event
+  NRF_TWIM0->EVENTS_STOPPED = 0;
+  // trigger the STARTRX task
+  NRF_TWIM0->TASKS_STARTRX = 1;
+  while( !(NRF_TWIM0->EVENTS_STOPPED) ){}
+}
+
+
+//
+//AS5013
+//
+void as5013_setup(){
+  NRF_GPIO->DIRSET = (1<<rst_pin); //set AS5013 nRESET pin as output
+  NRF_GPIO->OUTCLR = (1<<rst_pin); //hardware reset
+  delayMicroseconds(10);
+  NRF_GPIO->OUTSET = (1<<rst_pin); //turn on as5013
+  delayMicroseconds(1000);
+
+  //Loop check ctrl_reg until the value F0h or F1h is present
+  delay(1); //in practice even no delay is fine.
+  //config sensor
+  //todo: experiment with setting values
+}
+void as5013_read(){
+  //read raw values
+  twi_set_cnts(n_tx_bytes, n_rx_bytes);
+  txdata[0] = c_raw_values_start; //set up to read from this address
+  twi_tx();
+  twi_rx();
+  //assume idle mode, so we must read from Y_res_int register at end to trigger new conversion
+  twi_set_cnts(1, 1);
+  txdata[0] = y_res_reg;
+  twi_tx();
+  twi_rx(); 
+}
+
+//
+//main
+//
+void setup() {
+  Serial.begin(115200);
+  //uarte_setup();
+  twi_setup();
+  as5013_setup();
+  radio_setup();
   while(1){
-    //Serial.println("start txing");
-    txdata[0] = c_raw_values_start; //set up to read from address
-    twi_tx();
-    //Serial.println("done txing");
-    //Serial.println("start rxing");
-    twi_rx();
-    //Serial.println("done rxing");
-    
-    c1 = (((int16_t)rxdata[2])<<8 + (int16_t)rxdata[3]) - (((int16_t)rxdata[0])<<8 + (int16_t)rxdata[1]);
-    c2 = (((int16_t)rxdata[6])<<8 + (int16_t)rxdata[7]) - (((int16_t)rxdata[4])<<8 + (int16_t)rxdata[5]);
-    c3 = (((int16_t)rxdata[10])<<8 + (int16_t)rxdata[11]) - (((int16_t)rxdata[8])<<8 + (int16_t)rxdata[9]);
-    c4 = (((int16_t)rxdata[14])<<8 + (int16_t)rxdata[15]) - (((int16_t)rxdata[12])<<8 + (int16_t)rxdata[13]);
-    c5 = (((int16_t)rxdata[18])<<8 + (int16_t)rxdata[19]) - (((int16_t)rxdata[16])<<8 + (int16_t)rxdata[17]);
-    Serial.println("Raw sensor values");
-    Serial.println(c1);
-    Serial.println(c2);
-    Serial.println(c3);
-    Serial.println(c4);
-    Serial.println(c5);
+    if (millis() - last_tx_time > tx_period){
+      as5013_read();
+      radio_buffer[0] = 1; //send a move command
+      radio_buffer[1] = 10; //move 10 steps forward
+      radio_send(); //send command
+      int result = radio_recv(); //wait for response
+      //getting false positives...
+      Serial.print("buffer: ");
+      Serial.println(radio_buffer[1]);
+      Serial.print("result: ");
+      Serial.println(result);
+
+      //NRF_UARTE0->TXD.PTR = (uint32_t)(&rxdata);  //reset pointer to start of buffer
+      //NRF_UARTE0->TASKS_STARTTX = 1;  //trigger start task
+      last_tx_time = millis();     
+    }
   }
-  delay(100);
 }
 
 

as5013-test/nrf52-as5013/radio.h

+#define PACKET_BASE_ADDRESS_LENGTH  (2UL)  //Packet base address length field size in bytes
+#define PACKET_LENGTH 4
+static int16_t radio_buffer[PACKET_LENGTH] = {0};
+
+
+//
+//RADIO
+//
+void radio_setup(){
+  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);
+
+  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_1Mbit << 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_Enabled << RADIO_PCNF1_WHITEEN_Pos) |
+                     ((PACKET_LENGTH) << RADIO_PCNF1_STATLEN_Pos) |
+                     (RADIO_PCNF1_ENDIAN_Big       << RADIO_PCNF1_ENDIAN_Pos)  |
+                     (2 << RADIO_PCNF1_BALEN_Pos);
+  NRF_RADIO->CRCCNF = (RADIO_CRCCNF_LEN_Three << RADIO_CRCCNF_LEN_Pos); // Number of checksum bits
+  NRF_RADIO->CRCINIT = 0xFFFFUL; // Initial value
+  NRF_RADIO->CRCPOLY = 0x18D; //x8 + x7 + x3 + x2 + 1 = 110001101 
+  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
+  NRF_RADIO->PACKETPTR = (uint32_t)&radio_buffer; //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);
+}
+
+void radio_wait_for_end(){ while(!(NRF_RADIO->EVENTS_END)); NRF_RADIO->EVENTS_END = 0;} //clear end event  
+void radio_wait_for_ready(){ while(!(NRF_RADIO->EVENTS_READY)); NRF_RADIO->EVENTS_READY = 0;} //clear ready event
+void radio_disable(){
+  NRF_RADIO->EVENTS_DISABLED = 0; //clear disabled event
+  NRF_RADIO->TASKS_DISABLE = 1;
+  while(!(NRF_RADIO->EVENTS_DISABLED)); 
+}
+void radio_send(){
+  NRF_RADIO->EVENTS_READY = 0; //clear ready event
+  NRF_RADIO->TASKS_TXEN=1; //trigger tx enable task
+  delayMicroseconds(20);
+  //radio_wait_for_ready(); //only generated when actually switching to tx mode
+  NRF_RADIO->TASKS_START=1;  //start
+  radio_wait_for_end();
+  //add wait for ack?
+}
+int radio_recv(){
+  //return 0 if success
+  NRF_RADIO->EVENTS_CRCOK = 0; 
+  NRF_RADIO->EVENTS_CRCERROR = 0; 
+  NRF_RADIO->EVENTS_DEVMATCH = 0;
+  while(true){
+    NRF_RADIO->EVENTS_READY = 0; //clear ready event
+    NRF_RADIO->TASKS_RXEN=1; //trigger rx enable task
+    delayMicroseconds(20);
+    //radio_wait_for_ready(); //only generated when actually switching to rx mode 
+    NRF_RADIO->TASKS_START=1;
+    radio_wait_for_end();
+    Serial.println("got packet");
+    Serial.println(NRF_RADIO->EVENTS_CRCOK);
+    if ((NRF_RADIO->EVENTS_CRCOK == 1) && (NRF_RADIO->EVENTS_DEVMATCH == 1)){ break;}
+    delay(10);
+  }
+  return 0;
+}

as5013-test/nrf52-drv8825/nrf52-drv8825.ino

+#include "radio.h"
+uint16_t pwms[1] = {0};
+
+const uint8_t pin_mode1 = 3; //A1
+const uint8_t pin_mode0 = 0; //XL1
+const uint8_t pin_step = 1; //XL2
+const uint8_t pin_direction = 2; //A0
+const uint8_t pin_nrst = 27; //p27
+const uint8_t pin_ref = 26; //p26
+
+int i=0; //counter
+
+void stepper_setup(){
+  NRF_GPIO->DIRSET = (1 << pin_nrst); //set nrst/nslp pins as output
+  NRF_GPIO->OUTCLR = (1 << pin_nrst); //set nrst/nslp low to disable drv8825
+  NRF_GPIO->OUT = (0<<pin_nrst);
+
+  NRF_GPIO->DIRSET = (1 << pin_mode1) | (1 << pin_mode0); //set mode pins as output
+  NRF_GPIO->OUTCLR = (1 << pin_mode1) | (1 << pin_mode0); //set to full step mode
+
+  NRF_GPIO->DIRSET = (1 << pin_step) | (1 << pin_direction); //set step/dir pins as output
+
+  //Use PWM module to generate aref/bref
+  NRF_GPIO->DIRSET = (1<<pin_ref); //set ref pin as output
+  NRF_GPIO->OUTCLR = (1<<pin_ref); //set ref pin low
+  NRF_PWM0->PSEL.OUT[0] = (pin_ref << PWM_PSEL_OUT_PIN_Pos) | (PWM_PSEL_OUT_CONNECT_Connected << PWM_PSEL_OUT_CONNECT_Pos); //set aref pin to pwm out[0]
+  NRF_PWM0->ENABLE = (PWM_ENABLE_ENABLE_Enabled << PWM_ENABLE_ENABLE_Pos);
+  NRF_PWM0->MODE = (PWM_MODE_UPDOWN_Up << PWM_MODE_UPDOWN_Pos);
+  NRF_PWM0->PRESCALER = (PWM_PRESCALER_PRESCALER_DIV_1 << PWM_PRESCALER_PRESCALER_Pos); //16MHz tick
+  NRF_PWM0->COUNTERTOP = (1600 << PWM_COUNTERTOP_COUNTERTOP_Pos); //1 kHz pwm freq.
+  NRF_PWM0->LOOP = (PWM_LOOP_CNT_Disabled << PWM_LOOP_CNT_Pos);
+  NRF_PWM0->DECODER = (PWM_DECODER_LOAD_Common << PWM_DECODER_LOAD_Pos) | (PWM_DECODER_MODE_RefreshCount << PWM_DECODER_MODE_Pos);
+  pwms[0] = 1500; //50% duty cycle to test
+  NRF_PWM0->SEQ[0].PTR = ((uint32_t)(pwms) << PWM_SEQ_PTR_PTR_Pos);
+  NRF_PWM0->SEQ[0].CNT = (1 << PWM_SEQ_CNT_CNT_Pos);
+  NRF_PWM0->SEQ[0].REFRESH = 0;
+  NRF_PWM0->SEQ[0].ENDDELAY = 0;
+  NRF_PWM0->TASKS_SEQSTART[0] = 1;
+  delay(1); //give aref filter time to settle.
+}
+
+void parse_command(){
+  //interpret command from radio for stepper actions
+  //TODO: add commands for enable/disable driver, setting current limit, setting microstepping
+  if( radio_buffer[0] == 1 ){
+    //move by commanded number of steps
+    if (radio_buffer[1] > 0){
+      NRF_GPIO->OUTSET = (1<<pin_direction); //set direction forwards      
+    } else {
+      NRF_GPIO->OUTCLR = (1<<pin_direction); //set direction backwards    
+    }
+    for(i=0; i<radio_buffer[1]; i++){
+      NRF_GPIO->OUTSET = (1<<pin_step);
+      delay(10);
+      NRF_GPIO->OUTCLR = (1<<pin_step);
+      delay(1);        
+    }
+    
+    //reset radio buffer
+    for(i=0; i<PACKET_LENGTH; i++){
+      radio_buffer[i] = 0;
+    }
+  } else{
+    //unrecognized command, set radio buffer to all -1
+    for(int i=0; i<PACKET_LENGTH; i++){
+      radio_buffer[i] = -1;
+    }      
+  }
+}
+
+
+void setup() {
+
+  Serial.begin(115200);
+  
+  //Switch to internal LFCLK to disconnect from XL1 and XL2
+  NRF_CLOCK->LFCLKSRC = 0; //disconnect XL1 AND XL2 FROM LFCLK?
+  NRF_CLOCK->EVENTS_LFCLKSTARTED = 0;
+  NRF_CLOCK->TASKS_LFCLKSTART    = 1;
+  while (NRF_CLOCK->EVENTS_LFCLKSTARTED == 0) {}
+
+  stepper_setup();
+  radio_setup();
+
+  NRF_GPIO->OUTSET = (1<<pin_nrst); //set nrst/nslp high to enable drv8825
+
+  //debug transmit loop
+  while(true){
+    radio_send();
+    delay(10);
+  }
+
+  while (true) {
+    int result = radio_recv(); //wait until recieve
+    if (result==0){
+      //no crc error
+      parse_command();
+    } else{
+      //incoming crc error, set radio buffer to all -2
+      for(int i=0; i<PACKET_LENGTH; i++){
+        radio_buffer[i] = -2;
+      }  
+    }
+    radio_send(); //send back radio buffer when done
+  }
+}
+
+void loop() {}
+
+
+// draft for using timer for pwm
+
+  //NRF_TIMER1->MODE = (TIMER_MODE_MODE_Timer << TIMER_MODE_MODE_Pos) & TIMER_MODE_MODE_Msk;
+  //NRF_TIMER1->BITMODE = (TIMER_BITMODE_BITMODE_16Bit << TIMER_BITMODE_BITMODE_Pos) & TIMER_BITMODE_BITMODE_Msk;
+  //NRF_TIMER1->PRESCALER = (7 << TIMER_PRESCALER_PRESCALER_Pos) & TIMER_PRESCALER_PRESCALER_Msk;
+  //NRF_TIMER1->SHORTS = ((TIMER_SHORTS_COMPARE0_CLEAR_Enabled << TIMER_SHORTS_COMPARE0_CLEAR_Pos) & TIMER_SHORTS_COMPARE0_CLEAR_Msk);
+  //NRF_TIMER1->CC[0] = (1 << 15); //50% duty cycle to test
+
+  //enable PPI channel 0 for compare task setting pin high
+  //NRF_PPI->CHEN = (PPI_CHEN_CH0_Enabled << PPI_CHEN_CH0_Pos) & PPI_CHEN_CH0_Msk;
+  //NRF_PPI->CH[0].EEP = (uint32_t)&NRF_TIMER1->EVENTS_COMPARE[0];
+  //NRF_PPI->CH[0].TEP = (uint32_t)&NRF_GPIOTE->TASKS_OUT[0];
+  //enable PPI channel 1 for compare overflow setting pin low
+  //NRF_PPI->CHEN = (PPI_CHEN_CH1_Enabled << PPI_CHEN_CH1_Pos) & PPI_CHEN_CH1_Msk;
+  //NRF_PPI->CH[0].EEP = (uint32_t)&NRF_TIMER1->EVENTS_;
+  //NRF_PPI->CH[0].TEP = (uint32_t)&NRF_GPIOTE->TASKS_OUT[1];
+
+  //NRF_TIMER1->TASKS_START = 1;  //start timer

as5013-test/nrf52-drv8825/radio.h

+#define PACKET_BASE_ADDRESS_LENGTH  (2UL)  //Packet base address length field size in bytes
+#define PACKET_LENGTH 4
+static int16_t radio_buffer[PACKET_LENGTH] = {0};
+
+
+//
+//RADIO
+//
+void radio_setup(){
+  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);
+
+  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_1Mbit << 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_Enabled << RADIO_PCNF1_WHITEEN_Pos) |
+                     ((PACKET_LENGTH) << RADIO_PCNF1_STATLEN_Pos) |
+                     (RADIO_PCNF1_ENDIAN_Big       << RADIO_PCNF1_ENDIAN_Pos)  |
+                     (2 << RADIO_PCNF1_BALEN_Pos);
+  NRF_RADIO->CRCCNF = (RADIO_CRCCNF_LEN_Three << RADIO_CRCCNF_LEN_Pos); // Number of checksum bits
+  NRF_RADIO->CRCPOLY = 0x18D; //x8 + x7 + x3 + x2 + 1 = 110001101 
+  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
+  NRF_RADIO->PACKETPTR = (uint32_t)&radio_buffer; //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);
+}
+
+void radio_wait_for_end(){ while(!(NRF_RADIO->EVENTS_END)); NRF_RADIO->EVENTS_END = 0;} //clear end event  
+void radio_wait_for_ready(){ while(!(NRF_RADIO->EVENTS_READY)); NRF_RADIO->EVENTS_READY = 0;} //clear ready event
+void radio_disable(){
+  NRF_RADIO->EVENTS_DISABLED = 0; //clear disabled event
+  NRF_RADIO->TASKS_DISABLE = 1;
+  while(!(NRF_RADIO->EVENTS_DISABLED)); 
+}
+void radio_send(){
+  NRF_RADIO->EVENTS_READY = 0; //clear ready event
+  NRF_RADIO->TASKS_TXEN=1; //trigger tx enable task
+  delayMicroseconds(15);
+  //radio_wait_for_ready(); //only generated when actually switching to tx mode
+  NRF_RADIO->TASKS_START=1;  //start
+  radio_wait_for_end();
+  //add wait for ack?
+}
+int radio_recv(){
+  //return 0 if success
+  NRF_RADIO->EVENTS_CRCOK = 0; 
+  NRF_RADIO->EVENTS_CRCERROR = 0; 
+  while(true){
+    NRF_RADIO->EVENTS_READY = 0; //clear ready event
+    NRF_RADIO->TASKS_RXEN=1; //trigger rx enable task
+    delayMicroseconds(15);
+    //radio_wait_for_ready(); //only generated when actually switching to rx mode 
+    NRF_RADIO->TASKS_START=1;
+    radio_wait_for_end();
+    if (NRF_RADIO->EVENTS_CRCOK == 1){ break;}
+  }
+  return 0;
+}