• State Resolved
  • Locked Locked
  • Replies 2 replies
  • Subscribers 53 subscribers
  • Views 388 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

Original question:

CC1101 2-FSK - help needed

CC1101: Disable Packet Length Byte on Packet Transmit

terry gunson
Prodigy 10 points
Part Number: CC1101

I need to communicate with a non-C1101 device. It uses a simple packet format. The Sync and Preamble are defined and then the data payload is 14 bytes. Using RF Studio I have been able to set up most parameters. Using a SDR and RTL_433 to decode the signal (it has a built in decoder for the device I am looking at) it shows the correct sync, preamble and data payload - however the CC1101 is inserting the packetlen byte as the first following the preamble. My understanding from the CC1101 and CC430 datasheets is that this is optional, however the actual optional mode is not decleared. The CC430 guidance seemed to indicate that it was not used for variable packet length mode, I have tried fixed, variable and infinite but it does not seem to change the packet being sent.

THe CC1101 is being driven from an ESP32 - the init code writes the RF Studio settings to the registers. As indicated I have tried all three packet length options but it does not change the output..


SpiWriteReg(CC1101_SYNC1,0x2D);

SpiWriteReg(CC1101_SYNC0,0xD4);

SpiWriteReg(CC1101_PKTLEN,0x0E);

SpiWriteReg(CC1101_PKTCTRL1,0x00);

SpiWriteReg(CC1101_PKTCTRL0,0x00);

What am I missing??

  • +1
    TI__Guru* 79361 points

    No matter is you are using fixed or variable packet length on your CC1101 in TX mode, the device is not capable of inserting any length byte automatically. Preamble and sync is inserted automatically, and after sync is sent, the radio will simply transmit whatever the application has written to the TX FIFO.

    If the transmitter is configured for fixed packet length mode, it will transmit PKTLEN number of bytes from the TX FIFO, if it is configured for variable packet length mode, it will transmit n + 1 number of bytes from the TX FIFO, where n is the first byte written to the FIFO.

    BR

    Siri

  • 0 in reply to Siri
    Prodigy 10 points

    Thanks Siri,

    I had a feeling it was not the CC1101 - and you confirmed it. I found that the driver software I was using was preloadng the FIFO register with the packet length so issue resolved.

    Cheers