SmartRF Studio 7 version 2.18
CC1101 + SmartRF04eb + Arduino Uno
Synchronous serial mode, 4-FSK modulation

RXFIFO_OVERFLOW error when selecting continuous rx/synchronous serial mode and 4-FSK modulation format.
In RF device command screen clicking read rx fifo returns nothing. After SRES/SFRX command strobes still overflow error.


https://i.ibb.co/2P1Rk9x/rxfifo-overflow.jpg

When selecting 2-FSK and while RX is executing (Start button clicked), it is possible to change the modulation format to 4-FSK without overflow error. Menu item settings -> log to file, log file content when changing 2-FSK to 4-FSK.
13:38:38.088  MDMCFG2          0x00 2 W
13:38:38.103  FREND0           0x10 2 W
13:38:40.807  MDMCFG2          0x40 2 W
13:38:40.807  FREND0           0x10 2 W

https://i.ibb.co/qMPkds1/fsk4run.jpg

I tested this with two setups: CC Debugger + CC1101 and SmartRF04EB + CC1101.

 

Arduino code for receiving clock/data. IOCFG2 (serial clock) connected to Arduino digital pin 3 and IOCFG0 (serial data) connected to Arduino digital pin 2. CC1101 carrier sense signal should be connected also, but my CC1101 module has only GDO0 and GDO2 pins.

#define GDO0_PIN    2
#define GDO2_PIN    3
#define DATA_SIZE   64

#define pinOfPin(P)\
  (((P)>=0&&(P)<8)?&PIND:(((P)>7&&(P)<14)?&PINB:&PINC))
#define pinIndex(P)((uint8_t)(P>13?P-14:P&7))
#define pinMask(P)((uint8_t)(1<<pinIndex(P)))

#define isHigh(P)((*(pinOfPin(P))& pinMask(P))>0)
#define isLow(P)((*(pinOfPin(P))& pinMask(P))==0)
#define digitalState(P)((uint8_t)isHigh(P))

uint8_t data[DATA_SIZE];
volatile uint16_t index = 0;
volatile bool printData = false;

void setup() {
  Serial.begin(57600);
  pinMode(GDO0_PIN, INPUT);
  pinMode(GDO2_PIN, INPUT);

  memset(data, 0, sizeof(data));

  attachInterrupt(digitalPinToInterrupt(GDO2_PIN), isr, FALLING);
}

void loop() {
  uint8_t l = 0;
  if (printData) {
    Serial.print(F("\r\n\r\n"));
    for (uint16_t i = 0; i < index; i++) {
      Serial.print(data[i], HEX);
      l++;
      if (l == 31) {
        Serial.println();
        l = 0;
      }
    }
    index = 0;
    printData = false;
  }
}

void isr() {
  static uint8_t p = 0;
  static uint8_t v = 0;
  if (!printData) {
    // msbfirst (lsbfirst << n;)
    v |= digitalState(GDO0_PIN) << (7 - p);
    p++;
    if (p == 8) {
      data[index] = v;
      v = 0;
      p = 0;
      index++;
      if (index == DATA_SIZE) {
        printData = true;
      }
    }
  }
  else {
    if (index > 0) {
      p = 0;
      printData = true;
    }
  }
}