CC1200: RCOSC is deactivated, but timeout(t_event0) occures

Marco Nestel

Prodigy 10 points

Part Number: CC1200

Hi,

At startup, I set GPIO0 to Mode "WOR_EVENT0 (0x37)" and the registers "WOR_CFG0", "WOR_CFG1" to default value.

Before I set cc1200 to sleep mode (eWOR), I enable the RCOSC calibration and activate the RCOSC.

After this, I send an IDLE-Strobe, wait for calibration and at least a WOR-Strobe.

Now the GPIO0 is set all time the "t_event0" timeout occures.

--> This is like expect.

After wake-up, I want to disable the RCOSC and write an "1" to WOR_CFG0.RC_PD register.

But at this time, the "t_event0" timeout still occures and set the GPIO0.

--> I expect, this will not occure, after deacivation of RCOSC.

In the CC1200 UserGuide it is recommended, to deacivate the RCOSC, in case of long RX/TX periodes.

So my question is now, how to deactivte the RCOSC correctly, or is it normal, that the timeout occures with a deactivated RCOSC?

Best regards

8 months ago

0 Siri 8 months ago

TI__Guru* 81171 points

You must not confuse deactivating the RCOSC calibration (which is what the user guide states) with deactivating the RCOSC itself. calibration is controlled through RC_MODE, powering on/off the RCOSC is controlled via RC_PD.

The RCOSC needs to run all the time, but calibration can be turned off.

The EVENT1 will not happen if the RC_PD = 1

I checked this with a test doing the following:

// Initialize MCU and peripherals
initMCU();

// Write radio registers
registerConfig(); // WOR_CFG0 = 0x20

// Calibrate radio
trxSpiCmdStrobe(CC120X_SCAL);

// Wait for calibration to be done (radio back in IDLE state)
do {
    cc120xSpiReadReg(CC120X_MARCSTATE, &marcState, 1);
} while (marcState != 0x41);

// Calibrate the RCOSC
calibrateRCOsc();
    
// Output Event 0 and EVENT1 on GPIO for debugging;
    
  
// Set radio in RX Sniff Mode
trxSpiCmdStrobe(CC120X_SWOR); // After this strobe the WOR will work as normal
        
// Delay to wath the GPIOs

temp = 0x21;

// Write new register value
cc120xSpiWriteReg(CC120X_WOR_CFG0, &temp, 1); // turn off RCOSC
    
// Set radio in RX Sniff Mode
trxSpiCmdStrobe(CC120X_SWOR); // After this the EVENT will not happen since the RXOSC is not running
        
while(1);

        // Wait for packet to be received
        while(packetSemaphore != ISR_ACTION_REQUIRED);

the first time the SWOR is issues WOR will work as normal

The second time, no events will happen

Routine for manual calibration of RCOSC:

/*******************************************************************************
*   @fn         calibrateRcOsc
*
*   @brief      Calibrates the RC oscillator used for the eWOR timer. When this
*               function is called, WOR_CFG0.RC_PD must be 0
*
*   @param      none
*
*   @return     none
*/
static void calibrateRCOsc(void) {

    uint8 temp;

    // Read current register value
    cc120xSpiReadReg(CC120X_WOR_CFG0, &temp,1);

    // Mask register bit fields and write new values
    temp = (temp & 0xF9) | (0x02 << 1);

    // Write new register value
    cc120xSpiWriteReg(CC120X_WOR_CFG0, &temp,1);

    // Strobe IDLE to calibrate the RCOSC
    trxSpiCmdStrobe(CC120X_SIDLE);

    // Disable RC calibration
    temp = (temp & 0xF9) | (0x00 << 1);
    cc120xSpiWriteReg(CC120X_WOR_CFG0, &temp, 1);
}

Siri

Sub-1 GHz

Sub-1 GHz forum

CC1200: RCOSC is deactivated, but timeout(t_event0) occures