Re: RP400 40-pin connector

On Thu, 15 Aug 2024 13:13:57 +0200, albert@spenarnc.xs4all.nl wrote:

In article <d21ibjdvt6odqium3ado62ob1e7sa6n9hc@4ax.com>,
John Larkin  <jjlarkin@highlandtechnology.com> wrote:

I want to use an Raspberry Pi 400 (the keyboard thing) as the
dev/debug system for an RP2040 based product.
>
https://www.amazon.com/Raspberry-Computer-Keyboard-Layout-Kabel/dp/B08QCQVWH2
>
It has a 40-pin connector on the back. Various sources say that pins 1
3 and 5 are either GPIO ports 8 9 and 7 or maybe 2 3 and 4.
>
Sometimes the pins are labeled WPI and BCM. Wot's that?
>
https://www.amazon.com/Coolwell-Waveshare-Raspberry-Adapter-Expansion/dp/B08RZCR7S8
>
I can fix most mistakes there in software, just by reassigning port
names. But two pins are critical, the SWDIO and SWCLK debug lines out
to a Pi Pico or to the 2040 chip.
>
I suspect that on the Pi 400 pin 18 is GPIO5 = SWDIO and pin 22 is
GPIO6 = SWCLK.
>
Is that right? Does that actually work?
>
I also note that some people also connect the UART tx/rx between the
Pi400 and a Pico for debugging. Should I do that too? Does it help
software development?

>
Is the schematics from the R Pi 400 not available?

Yes, but the port pin nunbering is different from the Pi 4 and 5, so I
was concerned about which pins to connect to a Pico (or a 2040 chip)
for program loading and debugging.

This apparently works

https://www.dropbox.com/scl/fi/sd8mkqz3rw55fcevjouvi/OKdo_Pi400_debug_Pico.jpg?rlkey=kb5xjo75n5e5k3ncy4qs2caur&raw=1

and one can actually count the pins on the connectors.

One of my guys is hacking some connections and verifying. We're laying
out some PCBs for debugging and production test, and we need to get
the pins right.

I have the orangepi 800. The schematics are such that I can trace the
connector pins to the soc pins. The RK3399 is fully documented.
Mapping the io I can do "das blinken light" on the 26 pin (rp1
compatible) connector, using ciforth (a Forth developed by me).
Or light the upper case or numlock leds.
>

>
Thanks!