CC1101 asynchronous tx deviation

Could you please define what you mean by deviation and how you measure it? Also how much deviation you see?

im measuring the CC1101's async tx (from cc1101 -> mcu) with a logic analyzer. What i mean by deviation is the difference in length in transitions of several repeating signals from my remote control. when i compare the output of the cc1101 with the signal output of a passive rx receiver the repeating signals seems to stay the same.

You say you measure CC1101 -> mcu. If you are using async tx the communication would go from mcu -> CC1101? Which pin have you connected the logic anal. to? Please provide plots of what you are seeing.

It has been a while now, unfortunately i had to work on a other project. My apologies for that.

We are using the CC1101 as a generic receiver as well as a generic transmitter. We therefore chose to use the asynchronous serial mode for both rx and tx. Both the GD0 and GD02 pins are connected to an microcontroller. Both mcu gpio's are timer gpio's. The tx timer generates arbitrary signals while the rx gpio captures received signals both coming from the CC1101.

Lets take a look at the pictures in the attachment:

This is a print screen taken from a logic analyzer.

- The Microcontroller measurement (channel 3) represents the direct tx output to the GD0 input of the CC1101 (in TX mode)

-  The CC1101 dev RX measurement (channel 4) represents the direct rx from the GDO2 output of the  CC1101 dev kit's  (in RX Mode).

Both CC1101's uses the same configuration. Although, 1 CC1101 is in asynchronous tx and the other is in asynchronous rx.

As you can see, there is a significant deviation between both signals. The ideal situation would be that the microcontroller measurement is exactly the same as the CC1101 dev RX measurement. Is there anything in my configuration that you can find below that i can tweak to make this performance better?

I've tried multiple distances, but it doesnt make any difference. i also mentioned that the CC1101 randomly has noise when rx'ing. This probably has something to do with the surrounding noise.

The configuration i use:

0x0D,  // IOCFG2              GDO2 Output Pin Configuration
     0x2E,  // IOCFG1              GDO1 Output Pin Configuration
     0x0D,  // IOCFG0              GDO0 Output Pin Configuration
     0x47,  // FIFOTHR             RX FIFO and TX FIFO Thresholds
     0xD3,  // SYNC1               Sync Word, High Byte
     0x91,  // SYNC0               Sync Word, Low Byte
     0xFF,  // PKTLEN              Packet Length
     0x04,  // PKTCTRL1            Packet Automation Control
     0x32,  // PKTCTRL0            Packet Automation Control
     0x00,  // ADDR                Device Address
     0x00,  // CHANNR              Channel Number
     0x06,  // FSCTRL1             Frequency Synthesizer Control
     0x00,  // FSCTRL0             Frequency Synthesizer Control
     0x10,  // FREQ2               Frequency Control Word, High Byte
     0xB1,  // FREQ1               Frequency Control Word, Middle Byte
     0x21,  // FREQ0               Frequency Control Word, Low Byte
     0xF7,  // MDMCFG4             Modem Configuration
     0x93,  // MDMCFG3             Modem Configuration
     0x30,  // MDMCFG2             Modem Configuration
     0x00,  // MDMCFG1             Modem Configuration
     0x00,  // MDMCFG0             Modem Configuration
     0x15,  // DEVIATN             Modem Deviation Setting
     0x07,  // MCSM2               Main Radio Control State Machine Configuration
     0x0C,  // MCSM1               Main Radio Control State Machine Configuration
     0x18,  // MCSM0               Main Radio Control State Machine Configuration
     0x14,  // FOCCFG              Frequency Offset Compensation Configuration
     0x6C,  // BSCFG               Bit Synchronization Configuration
     0x04,  // AGCCTRL2            AGC Control
     0x10,  // AGCCTRL1            AGC Control
     0x50,  // AGCCTRL0            AGC Control
     0x87,  // WOREVT1             High Byte Event0 Timeout
     0x6B,  // WOREVT0             Low Byte Event0 Timeout
     0xFB,  // WORCTRL             Wake On Radio Control
     0x56,  // FREND1              Front End RX Configuration
     0x11,  // FREND0              Front End TX Configuration
     0xE9,  // FSCAL3              Frequency Synthesizer Calibration
     0x2A,  // FSCAL2              Frequency Synthesizer Calibration
     0x00,  // FSCAL1              Frequency Synthesizer Calibration
     0x1F,  // FSCAL0              Frequency Synthesizer Calibration
     0x41,  // RCCTRL1             RC Oscillator Configuration
     0x00,  // RCCTRL0             RC Oscillator Configuration
     0x59,  // FSTEST              Frequency Synthesizer Calibration Control
     0x7F,  // PTEST               Production Test
     0x3F,  // AGCTEST             AGC Test
     0x81,  // TEST2               Various Test Settings
     0x35,  // TEST1               Various Test Settings
     0x09,  // TEST0               Various Test Settings 

the Patable:

[0] = 0x00, [1] =  0xC0

Greets,

Reinier

Sorry, this ended a bit too far down in my mailbox.

It is a given delay both through the Rx and Tx chain in CC1101. From the moment you apply a signal to the GDO pin there will be some delay due to the propagation through logic etc before the signal is sent from the antenna. The same in Rx, it will be some delay through the Rx chain due to filtering and ADC delay. If I don't misunderstand your plots it's what you are seeing.