Q2687 Parallel Bus active on bootup

Hi, I have a Q2687 running 7.47.4 firmware and no Open AT. When I scope the data/address lines on the parallel bus there seems to be activity from boot up, is there a reason for this and can I stop it?


Not sure what activity you are seeing. In the table for the parallel interface there are only two lines that are an undefined state on power up, that is 51/CS2 and 53/A24 (the reset are pulled down or a 1), both of the lines are multiplexed with GPIO’s so you could try assigning them to be GPIO’s and setting them to a value on start up to see if that makes a difference. I suspect it won’t though as typically they are undefined on start up because the chipset is doing something with them that cannot be set until the firmware is able to take over from the pure hardware power up of the unit.




Yes I agree the reset values are low (as described in the manual) for the pins I am interested in and when I measure them they are, but only for a short amount of time. For example I measured the D7 and D8 (pins 99 and 100) on our old scope several tens of seconds after reset and I get the following:

From the Q2687 product technical spec suggest these pins are not muxed with anything else, but I could reading the wrong document. Also the ADL documentation seems to suggest that you need to subscribe to the service before it will do anything, which I am not because at+wopen=0.