On Thu, 7 Jan 2021, Ralph Stirling wrote:
Date: Thu, 7 Jan 2021 22:05:32 +0000
From: Ralph Stirling <ralph.stirl...@wallawalla.edu>
Reply-To: "Enhanced Machine Controller (EMC)"
<emc-users@lists.sourceforge.net>
To: "emc-users@lists.sourceforge.net" <emc-users@lists.sourceforge.net>
Subject: [Emc-users] Rpi 3b+ to 7i90hd
I have a Raspberry Pi 3b+ successfully talking to a
Mesa 7c81, but am now trying to get it working with
a 7i90hd. I have a very compact pcb made to go
from the 2x20 header on the pi to the 2x13 header
on the 7i90hd. It is wired:
Signal Rpi 7i90hd
SDI 19 13
SDO 21 15
SCK 23 11
SCS 24 17
+5V 2,4 26
GND 6,9,20,25,30,34,39 10,12,14,16,18,20,22,24
My test is:
$ mesaflash --device 7i90hd --addr /dev/spidev0.0 --spi --readhmid
Response is:
unable to set bpw32, fallback to bpw8
Unexpected cookie at 0100..0110:
00000000 00000000 00000000
No 7I90HD board found
Since a 7c81 works, it would seem my software setup is ok.
The problem would seem to lie with either my little adapter
board or with the 7i90hd. I have a bypass cap right between
pins 4 and 6 on the RPi connector (22uF 0805 ceramic). Do
I need to use a four layer board to have sufficient ground
plane? I have copper pour on the top and bottom of the board,
but it did not go between pins of the connectors.
Any suggestions?
Thanks,
-- Ralph
Looks right
2 layer should be fine as long as the ground is solid (wide)
between the 7I90 and the RPI (and lo longer than a couple of
inches
You might try adding a pullup to SDO (7I90 15) to see if you read
0xFFFFFFFF which would indicate the the 7I90 is not driving SDO
Sure you have a SPI config in the 7I90?
Peter Wallace
Mesa Electronics
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