Hi guys,

I small but annoying problem with the FT232BM chip I am hoping someone has a
clever solution too ...

Unlike the MAX232 chip, the FT232BM is not "on" unless a USB connection is
established with the chip.  This means that it misses the first couple of
receive bytes and garbles the first couple of sent bytes when you first plug
it in, assumably this is because the chip needs a little time to settle, the
crystal to stabilise, etc, etc.  Everything starts working fine after the
first few bytes.

I realise I am probably exacerbating the issue by not using the same crystal
for the PIC as for the FT USB chip, but I need to run my PIC at 20Mhz, and
the USB chip requires 6MHz, so I am using two crystals.

I have seen circuits where the DTR line from the USB chip is inverted and
tied to MCLR on the PIC, holding the PIC in reset whenever there is not a
USB cable plugged in, but this is not acceptable when you want to have the
PIC running regardless of whether or not a USB cable is plugged in or not.

What would be the best way to incorporate this settling time for the chip in
a software based solution.  I could always tie the DTR or another suitable
serial pin (maybe RTS or CTS for example) to another PIC pin and monitor the
pin, not sending anything and just ignoring the receive buffer and clearing
any overflows, etc., until that pin goes high, but I am short of PIC pins
and would prefer to try and find a way that does not require such a pin
connection.

Any suggestions anyone ?

Rgs
Ian.

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