FTDI USB interface chips

It turned out that I couldn't get flow control to work with the built-in drivers. I had to install the FTDI drivers. Now, the flow control appears to be working.

Hello again,

That's interesting, i never did it any other way then installing the FTDI drivers.
One 'cable' i got in the past had plug and play drivers and that worked right off the bat. That used the Prolific chip i think. It's been a while now though since i did that, several years back when these cables first starting appearing on the market and were 20 bucks and up.

Both Mac and Windows started to include these drivers in their operating systems in recent years. I don't know exactly when. But if you tried to use one of these converters before the driver was part of the OS, then you would need to load the mfgr's driver.

Another update:
Using the internal 4 MHz clock, I wasn't able to communicate at rates higher than 19200 baud, because the error gets too high. It appears that a 3% error is OK, but above 19200, the error is in the 7% range and communications fail. I remember having read some asynch protocol standards many years ago that specified how far off the baud rate could be and still get good communications, but I don't remember what the numbers would be, though 5% rings a bell.

Anyway, the FTDI driver on the computer can be set to non standard baud rates. So, I picked ones that the PIC could generate exactly. After that, the communications have been flawless. I now have communications working perfectly at 250k baud which is faster than the PIC can generate data to send. Needless to say, I'm very impressed.

BobW said:

I remember having read some asynch protocol standards many years ago that specified how far off the baud rate could be and still get good communications, but I don't remember what the numbers would be, though 5% rings a bell.

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It is 9.5 baud from the beginning of the start bit to the middle of the stop bit. The error must be small enough so that this point shouldn't wonder away out of the boundaries of the stop bit. So, maximum allowable error is 0.5/9.5 = 5.2%. This is combined error for both devices, so each device must have error below 2.6%. At higher speeds where rise/fall times matter, it's less than this.

FTDI should be able to do few MBaud.

NorthGuy said:

FTDI should be able to do few MBaud.

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That's good to know. That should be as fast as I'm ever likely to need.

I love the Ch340g It's a great chip and it works very well I use it with my esp2866 at less then 25 cents you put one on anything to get usb to serial works at both 5 and 3 volt levels.

be80be said:

I love the Ch340g It's a great chip and it works very well I use it with my esp2866 at less then 25 cents you put one on anything to get usb to serial works at both 5 and 3 volt levels.

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Hi,

I have that on a couple products i have. Seems to work pretty well.