From: Patrick Menschel <menschel.p@posteo.de>
To: Marc Kleine-Budde <mkl@pengutronix.de>,
Drew Fustini <drew@beagleboard.org>
Cc: Oliver Hartkopp <socketcan@hartkopp.net>,
linux-can@vger.kernel.org, Josh S <josh@macchina.cc>
Subject: Re: mcp251xfd on RPi 5.4 downstream
Date: Mon, 2 Nov 2020 19:47:20 +0100 [thread overview]
Message-ID: <cd778ddb-eb0e-bff9-5c14-06731ffb35a0@posteo.de> (raw)
In-Reply-To: <9e9db79d-9357-19bd-0584-3f97ed49c731@posteo.de>
>> https://www.waveshare.com/w/upload/e/e2/2-CH-CAN-FD-HAT-Schematic.pdf
>>
>> Grmpf :/
>>
>>> This means that can1 cs is connected to pi header pin 26
>>
>> Both of rpi's SPI host drivers prefer to use GPIO chip selects by default, as
>> native chip selects have some limitations. And all three mcp251xfd overlays use
>> GPIO chip selects, this means you can use any free GPIO in the system for the
>> SPI chip select.
>>
>> Marc
>>
>
> It took me a while to realize but those pin numbers on the PCB are
> WPI := WiringPi numbers, not header pin numbers and not BCM pin numbers.
>
> The schematics also has the WPI column in the lower left section.
>
> https://pinout.xyz/pinout/wiringpi#
>
> --
> Patrick
>
It may be a blunt guess, but according to page 99
https://www.raspberrypi.org/documentation/hardware/raspberrypi/bcm2711/rpi_DATA_2711_1p0.pdf
Pin 26 is pulldown. So it works if it remains unused because the pin is
input with pulldown thus the chip is selected by default.
I don't know if the CE pin can actually work if there is no matching alt
function in pinselect register.
--
Patrick
next prev parent reply other threads:[~2020-11-02 18:47 UTC|newest]
Thread overview: 54+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-22 3:10 mcp251xfd on RPi 5.4 downstream Drew Fustini
2020-10-22 6:00 ` Drew Fustini
2020-10-22 6:33 ` Marc Kleine-Budde
2020-10-22 18:42 ` Drew Fustini
2020-10-25 4:30 ` Drew Fustini
2020-10-25 8:49 ` Oliver Hartkopp
2020-10-25 10:58 ` Marc Kleine-Budde
2020-10-25 17:43 ` Patrick Menschel
2020-10-25 18:14 ` Marc Kleine-Budde
2020-10-25 18:42 ` Patrick Menschel
2020-10-26 1:59 ` Drew Fustini
2020-10-26 2:50 ` Drew Fustini
2020-10-26 5:16 ` Patrick Menschel
2020-10-26 7:45 ` Marc Kleine-Budde
2020-10-26 9:40 ` Marc Kleine-Budde
2020-10-26 16:51 ` Patrick Menschel
2020-10-26 17:00 ` Marc Kleine-Budde
2020-10-27 2:22 ` Drew Fustini
2020-10-27 6:35 ` Drew Fustini
2020-10-27 7:06 ` Marc Kleine-Budde
2020-10-27 18:18 ` Patrick Menschel
2020-10-27 18:22 ` Marc Kleine-Budde
2020-10-28 1:57 ` Drew Fustini
2020-10-28 3:47 ` Drew Fustini
2020-10-28 7:57 ` Marc Kleine-Budde
2020-10-31 12:27 ` Drew Fustini
2020-10-31 15:14 ` Patrick Menschel
2020-10-31 15:35 ` Patrick Menschel
2020-10-31 21:57 ` Drew Fustini
2020-11-01 22:49 ` Drew Fustini
2020-11-02 7:25 ` Marc Kleine-Budde
2020-11-02 8:18 ` Marc Kleine-Budde
[not found] ` <CAPgEAj7LcX3cb+syhtR1i3Uo1XkYYFQ_wDPV8GniaA-YwPk2Hg@mail.gmail.com>
2020-11-02 11:00 ` Marc Kleine-Budde
[not found] ` <CAPgEAj7BTJyiBg4QkKuekYH0zyrA-10dby3Lgb5qj2uiD4ZOYQ@mail.gmail.com>
2020-11-02 14:22 ` mcp251xfd: loopback test on waveshare canfd hat Marc Kleine-Budde
2020-11-02 14:35 ` Drew Fustini
2020-11-02 14:38 ` Marc Kleine-Budde
2020-11-02 17:34 ` mcp251xfd on RPi 5.4 downstream Patrick Menschel
2020-11-02 18:47 ` Patrick Menschel [this message]
2020-11-02 18:57 ` Thomas.Kopp
2020-11-02 19:32 ` Patrick Menschel
2020-11-04 18:48 ` Patrick Menschel
2020-11-05 7:15 ` Marc Kleine-Budde
2020-11-05 18:11 ` Patrick Menschel
2020-11-06 9:00 ` Marc Kleine-Budde
2020-11-06 11:31 ` Patrick Menschel
2020-11-06 11:36 ` Marc Kleine-Budde
2020-11-06 11:46 ` Patrick Menschel
2020-11-05 8:08 ` Marc Kleine-Budde
2020-11-05 8:07 ` Marc Kleine-Budde
2020-11-02 7:55 ` Marc Kleine-Budde
2020-11-02 7:26 ` Marc Kleine-Budde
2020-10-26 7:43 ` Marc Kleine-Budde
2020-11-20 12:32 ` Marc Kleine-Budde
[not found] ` <CAEf4M_B68X2T0rkaq0tqahBFPc+Gbvac7-+G0j5jd-g4j+j01g@mail.gmail.com>
2020-11-20 13:16 ` Marc Kleine-Budde
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