Forum Discussion

Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
16 years ago

Problem with RTS and CTS signals of UART

Dear all

I am working on UART of NIOS II with EP1S10F 780C6 Board

i tried loopback mode (without RTS & CTS Signals) where i will type data on Hyperterminal and display back on hyperterminal through NIOS processor

For data i type by hand it works perfectly by displaying back the letters i type on hyperterminal

but when i try to send a text file through hyperterminal i see the data missing

So I added RTS & CTS signals to the design

Now nothing works even the letters i type by hand are not displayed back on hyperterminal

I have made the proper pin assignment for RXD TXD RTS and CTS signals as specified in the data sheet

I have set the flow control in the hyperterminal as "Hardware" in Hyperterminal

Please help me out Thanks In advance

Regards

M Kalyansrinivas

3 Replies

  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    15 years ago

    Dear all

    I still face the same issue

    I added Signal tap to the design and tried to capture the signals but i see the CTS stays high and RTS stays low all the time

    Will the UART transmission and reception works if i set the RTS and CTS signals in Sopc builder

    I connected the CTS pin of FPGA to CTS pin of RS232 and RTS to RTS pin of RS232

    Please give some idea to solve this problem

    regards

    M Kalyansrinivas
  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    15 years ago

    It is unlikely that the hardware will handle flow control automatically.

    The 'device driver' on the nios side will need to detect it's receive FIFO filling and monitor the 'RTS' input.

    If the rx fifo fills (or maybe a software fifo beneath the hw one) deassert CTS, if RTS is asserted stop transmitting.
  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    15 years ago

    Hi dsl

    Do you say that i need to change the way i code my HAL,by accessing the status registers when i include RTS/CTS signals

    Thanks in advance

    M kalyansrinivas