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Topic: Using Microchip MCP2200 instead of FTDI FT232 (Read 2864 times) previous topic - next topic

jtw11

I can see why you would want to be able to control the GP pins from the USB side, for things like MCU hard resets - but to make them uncontrollable from the UART side seems madness...

CrossRoads

What would you have the slave device do on the GPIO pins?
The part is a USB/TTL serial controller. The slave device can send back Clear To Send (CTS), and maybe one other control signal, that's really all the RS232 interface supports in a 9-pin connector.
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macegr


I can see why you would want to be able to control the GP pins from the USB side, for things like MCU hard resets - but to make them uncontrollable from the UART side seems madness...


Madness? THIS. IS. RS232.

It's a byte pipe. USB is able to control the GPIO pins because it sees the FTDI device as a structure with various elements, just one of which is a serial data link. On the uC side, it's just a hose containing bytes, there's no method for out-of-band signaling of other functions. Would you want the FTDI chip to contain some magic sequence of bytes that triggers the GPIO? What if in the course of transferring other data, that magic sequence occurs? Not a good idea.
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jtw11

Macegr, you make a very good point - if for some reason you're application needs to send the datastream that would toggle the GPIO, you're stuffed.

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