Questions about FT600 GPIO Configuration Strapping

Help Request
1

I have some old v1 modules both the Au and the Ft module. I was trying to develop module myself to communicate with the FT module myself and as I was debugging a few things I discovered that TXE_n is always high, even right after connecting to the computer, even though the FPGA has written nothing to the FT600. This had me searching through the schematic and FT60X manual when I noticed in the schematic that the GPIO pins were unconnected. This is somewhat worrying to me as the manual says:

GPOI[1:0] are multifunctional pins. The functions are configured by the chip configuration data. The default chip configuration sets the GPIO pins as FIFO mode configuration input. At the power up, FT600 or FT601 sets the chip to 245 synchronous FIFO mode or multi-channel FIFO modes depending on the GPIO[1:0] input, details in the table below:

The table says the GPIO pins must both be 0 to set the chip to the 245 synchronous FIFO mode.

I cannot see anything about default pull-downs or anything for those pins. Is this a possible cause for the issue I am seeing? If so, is there a way around this other than blue-wiring the board?

2

The GPIO shouldn’t be an issue. I believe you can just set the mode via the D3xx library regardless of the GPIO pins.

I’m not in the office today but I can dig up some example code we use to test the boards if you need it.

If I recall correctly, I ran into this issue before though and it turned out TXE_n would sometimes stay high until WR_n was asserted. If you look at the code for our module, when we have data to send we pull wr low and wait for txe to also go low.

There is an issue with the V1 Ft where it sometimes fails to enumerate if you have the board powered from the other USB port then plug in the Ft. This was caused by the AC coupling caps being on the wrong side of the multiplexer. Other than that, it shouldn’t have any hardware issues and I’ve used it quite extensively.

3

Ah, I see! Thank you so much for the pointers to the right direction, (also sorry for the late reply, I was away from electronics for most of the day.)