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CC2530 low UART baud rate issue

Sam Fazer
Prodigy 30 points

Other Parts Discussed in Thread: CC2530, SN65176B

Hi,

I have a scenario where 2 CC2530 EM were connected to 2 different computers through RS485 interface(No possibility for H/w flow control). I need to sent 8-byte packets between these computers through RS485 connected to these 2 Zigbee modules. When I set higher baud rates (like 38.4k or 57.6k or higher), I can get those bytes correct in the destination computer's Hyperterminal. But if I use a lower baud rate like 9600 or 19200, some of the bytes are lost or are received corrupted or with extra bytes. For eg: If I use 9600bps, the last 2 bytes are usually lost or are different from what I sent. Can someone help please?

Thanks,

Sam

  • 0
    TI__Mastermind 19350 points

    Looks like cumulative clocks/crystals are causing drift of more than half a bit at baud rates that aren't working for your setup - have you scoped it?  Can't you tweak or calibrate your design of the 485 drivers to match those on the PC card?

  • 0 in reply to Dirty Harry
    Prodigy 30 points

    Hi Harry,


    Thanks for the reply. But I dont have a high precision scope at my disposal which can show a bit-by-bit value or measure the baud rates. By 485 drivers, what do you mean? Is it at the PC side or in the Zstack? We use a TI Differential Bus Transceiver (SN65176B/SN65HVD485ESO8) on the EB. Then a RS485-to-USB converter to connect from the RS485 port in our Zigbee EB to a PC USB port and then use Windows Hyperterminal program to capture the bytes. Where/how can I tweak the drivers? I have attached our RS485 part from our Zigbee EB schematic FYR. Please help.

    Regards,

    Sam

    CC2530 RS485.pdf
  • 0 in reply to Sam Fazer
    Prodigy 30 points

    Hi,

    Anybody there to help! Any help would be appreciated.

     

    Thanks,

    Sam

     

    Sam Fazer said:

    Hi Harry,


    Thanks for the reply. But I dont have a high precision scope at my disposal which can show a bit-by-bit value or measure the baud rates. By 485 drivers, what do you mean? Is it at the PC side or in the Zstack? We use a TI Differential Bus Transceiver (SN65176B/SN65HVD485ESO8) on the EB. Then a RS485-to-USB converter to connect from the RS485 port in our Zigbee EB to a PC USB port and then use Windows Hyperterminal program to capture the bytes. Where/how can I tweak the drivers? I have attached our RS485 part from our Zigbee EB schematic FYR. Please help.

    Regards,

    Sam