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USB Low-Full-High Speed Peripherals

Anonymous
Not applicable

Is there any way to get a transmitter enable signal for controlling half-duplex RS485 driver chips such as the MAX1487 from the CY7C65213?

   

I hoped perhaps I could do this using the TXLED pin, but the data sheet says that is USB transmission not serial line transmission and in any case being specified for LED driving could one be sure of the timing?

   

An alternative is to drive this from one of the handshake outputs (DTR or RTS) and toggle it in software on the host. This is all very well on a microcontroller but is difficult to achieve satisfactorily through the layers of poorly specified mush PC operating systems impose between you and the hardware.

   

The competing chips from FTDI support this (TXEN output configurable in setup), but I really want to use Cypress for the wider voltage range and better integration. Is there any way of achieving this that I am missing?

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2 Replies
Anonymous
Not applicable

Hi,

   

You can make an ordinary GPIO for this purpose. Assert the GPIO before any transmit is being done.

   

Regards,

   

- Madhu Sudhan

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Anonymous
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Problem with this approach is that you cannot use the VCP and so cannot use a standard terminal emulator program. It really needs it to be driven by the chip which knows when it is actually transmitting rather than just buffering data. I'm afraid I'm moving back to the FT232R because of this missing feature.

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