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    rs232 communication speeds over Embedded linux ARM

    Posts: 2
    in Kernel Development

    Hi ,

    I am using ARM embedded linux 2.6.30 on a samsung s3c2440. When I try to transfer bulk data (eg. a database) over serial port, I am getting speed of around 2-3 kbps. I am using a rs232 interface from my PC to the ARM development kit. The same code on PC to PC transfer gives me speed of 20kbps.

    Is that the best speed I can get on an embedded platform. Can I do any to improve the performance, like mapping DMA channel for a UART or increasing the fifo size etc. etc.

    Please help.

    Thanks

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    Comments

    • Posts: 501
      What baud-rate and flow control are you using for the port? I have an ARM board w/ multiple rs-232 ports and can get 115kbps out of them.
    • Posts: 2
      Hi,

      I use a baudrate of 115200 and flow control is none.

      Once I changed the fifosize of the serial port from inside the driver, I was able to increase the speed a little bit (to 4kbps), but not considerably.

      woboyle, are you able to do the data transfer at a rate of 115kbps. If so, is your serial port using a DMA to transfer data. ? what is the value for fifosize ?

      Thanks
      gigin
    • Posts: 501
      The most important thing is to utilize hardware flow-control at those speeds, otherwise no matter how big, the fifo buffer overflows. I don't pay attention to the DMA transfer issue - the boards I use run a version of Debian Etch and the serial drivers are built into the kernel. I haven't futzed with their configuration - only file system support and such.
    • Posts: 182
      PC to PC transfer will be faster than PC to Embedded devices, due its Processor speed and a good enhanced OS will be in PC.

      ARM kit is a Embedded device, so, the speed will be obviously less than PC-PC communication. In you case PC to PC also slow, a dead slow.

      Check your settings in PC side too.
      Try to transfer files from 512kb then increase step by step and find out where the things are going wrong.
    • Posts: 1,114
      Six months later ... is the OP still around?

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