Communication works, turn on reference, expose clk

firmware/playground/playground.ino

 #include <SPI.h>
 
 #define nCS 46
+
 #define REG_ID 0x05
 #define REG_READ 0b01000000
+#define REG_WRITE 0b00000000
+#define REG_ADC_CONTROL 0x01 
+#define POWER_MODE_FULLPOWER 0b0000000010000000
+#define CLK_SEL_INTERNALANDPIN 0b0000000000000001
+#define REF_EN 0b0000000100000000
+
+void reset_comm(){
+  SPI.beginTransaction(SPISettings(84000000/128, MSBFIRST, SPI_MODE3));
+  for(unsigned i = 0; i < 8; ++i){
+    SPI.transfer(0xFF);
+  }
+  SPI.endTransaction();
+}
+
+//T must be either uint8_t, uint16_t or uint24_t
+template <class T>
+void SPIwrite(T data, uint8_t reg){
+  uint8_t wrbuf[] = {0, 0, 0, 0};
+  //set up write command
+  wrbuf[0] = reg | REG_WRITE;
+  uint8_t num_bytes = sizeof(data);
+  for(unsigned i = 0; i < num_bytes; ++i){
+    wrbuf[num_bytes-i] = data & 0xFF;
+    data >>= 8;
+  }
+  SPI.beginTransaction(SPISettings(84000000/128, MSBFIRST, SPI_MODE3));
+  SPI.transfer(wrbuf, num_bytes+1);
+  SPI.endTransaction();
+}
+
+//T must be either uint8_t, uint16_t or uint24_t
+template <class T>
+void SPIread(T& data, uint8_t reg){
+  uint8_t rdbuf[] = {0, 0, 0, 0};
+  //set up write command
+  rdbuf[0] = reg | REG_READ;
+  uint8_t num_bytes = sizeof(data);
+  SPI.beginTransaction(SPISettings(84000000/128, MSBFIRST, SPI_MODE3));
+  SPI.transfer(rdbuf, num_bytes+1);
+  SPI.endTransaction();
+  for(unsigned i = 1; i <= num_bytes; ++i){
+    data <<= 8;
+    data += rdbuf[i];
+  }
+}
+
+
 
 void setup() {
   Serial.begin(9600);
   digitalWrite(nCS, HIGH);
   pinMode(nCS, OUTPUT);
   SPI.begin();
+
+  delay(1000);
+
+  digitalWrite(nCS, LOW);
+
+
+  uint16_t data;
+  SPIread(data, REG_ADC_CONTROL);
+  
+  Serial.print("ADC_CONTROL: ");
+  Serial.print(data, BIN);
+  Serial.print("\n");
+  
+  //Turn on internal reference, expose MCLK
+  data |= CLK_SEL_INTERNALANDPIN | REF_EN;
+  Serial.print("Setting to ");
+  Serial.print(data, BIN);
+  Serial.print("\n");
+  SPIwrite(data, REG_ADC_CONTROL);
+
+  //Read ADC_CONTROL
+  SPIread(data, REG_ADC_CONTROL);
+  Serial.print("ADC_CONTROL: ");
+  Serial.print(data, BIN);
+  Serial.print("\n");
+
+  digitalWrite(nCS, HIGH);
+
 }
 
 void loop() {
-  SPI.beginTransaction(SPISettings(84000000/128, MSBFIRST, SPI_MODE3));
   digitalWrite(nCS, LOW);
-  SPI.transfer(REG_ID | REG_READ);
-  uint8_t id = SPI.transfer(0x00);
+  uint8_t id;
+  SPIread(id, REG_ID);
   digitalWrite(nCS, HIGH);
-  SPI.endTransaction();
-  Serial.print(id, HEX);
+  Serial.print(id, BIN);
+  Serial.print("\n");
   delay(1000);
 }