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Original question:

CC1101 OOK modulation (Register Configuration)

CC1101: No transmission on 433.92MHz OOK

Susan Mackay
Prodigy 10 points
Part Number: CC1101
Other Parts Discussed in Thread: TEST2

Tool/software:

I have my own circuit that duplicates the one in the data sheet for the C1101.

The driving MCU is a Seeed Studio Xiao ESP32S3 that is aso providing the 3.3V to the C1101.

I have a 26MHz crystal and I can see oscillations from that and also see the XTAL/192 on the GDO2 pin. (In my code I actually use this signal to determine the actual frequency of the crystal and set the FREQx registers.)

I am trying to use the OOK modulation but I'm not able to transmit after sending the STX strobe. (I think I'm getting something on receive but it appears random and does not relate to any signal that I'm sending from a known-good 433.92MHz OOK transmitter.) I have a RTL-SDR dongle that runs on a Windows 11 system and it sees other 433.92MHz signals. However, when the ESP32 toggles the GDO0 line (.5se high then .5 sec low; the returned status shows that the C1101 is in Tx mode) there is no response seen.

The configuration values are:

--- C1101 initialised - Status Registers now:
REG_IOCFG2 = 0x0d
REG_IOCFG1 = 0x2e
REG_IOCFG0 = 0x3f
REG_FIFOTHR = 0x07
REG_SYNC1 = 0xd3
REG_SYNC0 = 0x91
REG_PKTLEN = 0xff
REG_PKTCTRL1 = 0x04
REG_PKTCTRL0 = 0x32
REG_ADDR = 0x00
REG_CHANNR = 0x00
REG_FSCRTL1 = 0x0f
REG_FSCTRL0 = 0x00
REG_FREQ2 = 0x10
REG_FREQ1 = 0xc9
REG_FREQ0 = 0x58
REG_MDMCFG4 = 0x8c
REG_MDMCFG3 = 0x22
REG_MDMCFG2 = 0x30
REG_MDMCFG1 = 0x22
REG_MDMCFG0 = 0x00
REG_DEVIATN = 0x00
REG_MCSM2 = 0x07
REG_MSCM1 = 0x30
REG_MCSM0 = 0x04
REG_FOCCFG = 0x34
REG_BSCFG = 0x6c
REG_AGCTRL2 = 0x04
REG_AGCTRL1 = 0x00
REG_AGCTRL0 = 0x92
REG_WOREVT1 = 0x87
REG_WOREVT0 = 0x6b
REG_WORCTRL = 0xf8
REG_FREND1 = 0xb6
REG_FREND0 = 0x10
REG_FSCAL3 = 0xa9
REG_FSCAL2 = 0x0a
REG_FSCAL1 = 0x20
REG_FSCAL0 = 0x0d
REG_RCCTRL1 = 0x41
REG_RCCTRL0 = 0x00
REG_FSTEST = 0x59
REG_PTEST = 0x7f
REG_AGCTEST = 0x3f
REG_TEST2 = 0x88
REG_TEST1 = 0x31
REG_TEST0 = 0x0b
PA_TABLE[0] = 0x00
PA_TABLE[1] = 0xc0
PA_TABLE[2] = 0x00
PA_TABLE[3] = 0x00
PA_TABLE[4] = 0x00
PA_TABLE[5] = 0x00
PA_TABLE[6] = 0x00
PA_TABLE[7] = 0x00
PA_TABLE Index = 0x11

I have read the DN022 and tried to use the values suggested in that above.

However I can't use the SmartRF Studio as I have no idea what it needs (hardware-wise) to connect to my circuit. (BTW I'm retired and on a pension so purchasing additional interface devices is practially beyond my budget.) However the ESP32's SPI module is connecting very well and there does not appear to be any problem in that area.

Can someone please let me know if any of the above are wrong (and what they should be) and also if there is some sequence that I need to perform to get teh transmitter (and also probably the receiver) working?

Susan

  • 0
    TI__Mastermind 33170 points

    Hi,

    Please measure the conducted static unmodulated Tx carrier on your hardware as the first step.

    You can still use SmartRF studio to determine the default register settings to perform a static unmodulated Tx carrier even though being offline.

  • 0 in reply to RGW
    Prodigy 10 points

    Firstly thank you for your reply and my apologies for taking time to respond - I needed a day to check out what you said and then GrandParent duties got in the way.

    RE SmartRF - when I first installed that I thought that it needed to connect to the C1101 to work.  Thanks to your comment I see that there is an 'offline' mode and that looks like it has done the trick.

    I now can see the RF on my dongle. It was initially way off frequency (despite my measuring the crystal frequency and re-working the FREQ values) but I've managed to tweak the FREQ settings to bring (at least the fundamental - there seem to be a lot of harmonics for me to track down) to the correct frequency. (I also have the fundamental drift over the 500ms burst that I'm using to test but that is another issue).

    Also I seem to be getting the GDO2 signal of the RSSI threshold working (it goes high correctly but I seem to have some instability on how long it stays high after the other transmitter stops (again - that is another issue).

    So thank you for your assistant.

    Susan