Bug 760190 - Enabling BITMODE_CBUS increases serial baudrate
Enabling BITMODE_CBUS increases serial baudrate
Product: Fedora
Classification: Fedora
Component: libftdi (Show other bugs)
All All
unspecified Severity unspecified
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Assigned To: Lucian Langa
Fedora Extras Quality Assurance
Depends On:
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Reported: 2011-12-05 10:53 EST by Canyon Bliss
Modified: 2013-02-13 08:19 EST (History)
1 user (show)

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Doc Type: Bug Fix
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Last Closed: 2013-02-13 08:19:15 EST
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Description Canyon Bliss 2011-12-05 10:53:23 EST
Description of problem:
Using the CBUS pins as IO (bitbang mode) increases serial baudrate by a multiple of 4. That is, setting the bitmode to BITMODE_CBUS increases serial baudrate.

Version-Release number of selected component (if applicable):
libftdi 0.19-1

How reproducible:
Every time.

Steps to Reproduce:
1. Enable CBUS pins as bitbang IO (CBUS_IOMODE) in EEPROM.
2. Set bitmode to BITMODE_CBUS: ftdi_set_bitmode(&ftdic, 0xFF, BITMODE_CBUS)
3. Set baudrate: ftdi_set_baudrate(&ftdic, 115200)
4. Attempt serial communication
Actual results:
Unable to communicate with another serial device. Serial baudrate four times faster than it should be.

Expected results:
Serial communication succeeds. Serial baudrate is what it was set to.

Additional info:
I've only confirmed on FT232R because the only chip I have with CBUS IO is the FT232R.

I can provide scope traces if necessary.

Checking bitbang_enabled does not cover all cases. Perhaps, checking bitbang_mode should be done as well.

Dividing the baudrate setting by four is a workaround: ftdi_set_baudrate(&ftdic, (115200/4)).
Comment 1 Fedora End Of Life 2013-01-16 07:46:56 EST
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