tirsdag den 16. januar 2024 kl. 00.13.38 UTC+1 skrev john larkin:
On Mon, 15 Jan 2024 13:21:14 -0800 (PST), Lasse Langwadt Christensen
<lang...@fonz.dk> wrote:
mandag den 15. januar 2024 kl. 22.05.18 UTC+1 skrev john larkin:It doesn't say so, but when he says "raspberry pi" I think he means a
The Raspberry Pi pico has its 3-pin SWD debug port. I'd like to
connect it to the 40-pin header on the back of the Pi400, to use the
400 as the dev/debug platform for some RP2040-based boxes.
Has anyone done this? What Pi400 pins connect to the SWD port?
Googling doesn't help. I have the RP400 Beginners Guide book and it
doesn't mention doing this.
Anybody have links about doing this?
https://www.electronicshub.org/programming-raspberry-pi-pico-with-swd/
Pi3. I'll be using a Pi4, inside the Pi400 unit, but I expect the pins
are the same on its 40-pin header.
afaik the 40 pin header on all Pi's are compatible, except for maybe some of the alternate functions
and on the Pi5 the GPIOs are one the new RP1 chip via pci-e so probably adds a us of latency
It is linked in the description:
https://github.com/mschwingen/hardware/tree/master/JTAG_hat/pcb_ms_v3/Doc
It's basically a bunch of 74LVC2T45 (which handle the "one side powered >>down" as well as the level-shifting), plus open-drain drivers for the reset >>signals. Note that you need to switch direction for the SWDIO signal, the >>rest is unidirectional.
Do you think it's worth buffering the SW Debug pins?
I was thinking I
might buffer the clock, since it's unidirectional and maybe
edge/impedance sensitive.
I have no idea what the timing from the
Pi400 will be like, but people seem to use breadboards and dangling
wires and get away with it.
On 2024-01-16, John Larkin <jl@997PotHill.com> wrote:
It is linked in the description:
It's basically a bunch of 74LVC2T45 (which handle the "one side powered >>>down" as well as the level-shifting), plus open-drain drivers for the reset >>>signals. Note that you need to switch direction for the SWDIO signal, the >>>rest is unidirectional.https://github.com/mschwingen/hardware/tree/master/JTAG_hat/pcb_ms_v3/Doc >>>
Do you think it's worth buffering the SW Debug pins?
Definitely. Otherwise, when powering down one side of the link (eg. the >RP2040 target), current from any data line being "H" will flow through the >target's protection diodes into its VCC.
This leads to all kinds of problems (like the device not properly starting >when powered up again). It will probably survive, but it's unspecified >behaviour and may cause hours of debugging trouble.
The cheap solution is series resistors that limit the current to non-fatal >levels, but then you may have to lower the speed and may still experience >strange behaviour.
IMHO, at the price of a few LVC buffers, it is not worth leaving them out. >And with the buffers, you can handle targets running at voltages other than >3.3V.
I was thinking I
might buffer the clock, since it's unidirectional and maybe
edge/impedance sensitive.
You definitely need series resistors in the clock line to reduce reflections >- I had to add them on some other debug probe (BusBlaster, old revision) >where they were missing, causing errors at ~15cm cable length.
I have no idea what the timing from the
Pi400 will be like, but people seem to use breadboards and dangling
wires and get away with it.
It's the edge rate that matters, and the SWCLK input on the RP2040 will be >quite fast. Again, it's not worth saving some cents and have unreliable >operation afterwards.
cu
Michael
tirsdag den 16. januar 2024 kl. 22.16.13 UTC+1 skrev john larkin:
On 16 Jan 2024 19:04:14 GMT, Michael Schwingen
<news-15...@discworld.dascon.de> wrote:
On 2024-01-16, John Larkin <j...@997PotHill.com> wrote:The Pico schematic is instructive. It claims that the RP2040 chip has
It is linked in the description:
https://github.com/mschwingen/hardware/tree/master/JTAG_hat/pcb_ms_v3/Doc >> >>>
It's basically a bunch of 74LVC2T45 (which handle the "one side powered >> >>>down" as well as the level-shifting), plus open-drain drivers for the reset
signals. Note that you need to switch direction for the SWDIO signal, the >> >>>rest is unidirectional.
Do you think it's worth buffering the SW Debug pins?
Definitely. Otherwise, when powering down one side of the link (eg. the
RP2040 target), current from any data line being "H" will flow through the >> >target's protection diodes into its VCC.
This leads to all kinds of problems (like the device not properly starting >> >when powered up again). It will probably survive, but it's unspecified
behaviour and may cause hours of debugging trouble.
The cheap solution is series resistors that limit the current to non-fatal >> >levels, but then you may have to lower the speed and may still experience >> >strange behaviour.
IMHO, at the price of a few LVC buffers, it is not worth leaving them out. >> >And with the buffers, you can handle targets running at voltages other than >> >3.3V.
I was thinking I
might buffer the clock, since it's unidirectional and maybe
edge/impedance sensitive.
You definitely need series resistors in the clock line to reduce reflections
- I had to add them on some other debug probe (BusBlaster, old revision)
where they were missing, causing errors at ~15cm cable length.
I have no idea what the timing from the
Pi400 will be like, but people seem to use breadboards and dangling
wires and get away with it.
It's the edge rate that matters, and the SWCLK input on the RP2040 will be >> >quite fast. Again, it's not worth saving some cents and have unreliable
operation afterwards.
cu
Michael
no diodes to its Vcc, and the pico has no added resistors that might
limit current in logic signals. There is one fet in the VSYS adc path
that I don't understand.
it is there to stop back feeding the chip thought the ADC pin when the 3.3V is off.
The ADC capable pins have diodes to VCC, it is only the FT pins that doesn't have diodes
This is a first pass at the dev board.
https://www.dropbox.com/scl/fi/709v4pqjhe91jnwqh4wvg/Z566_Sch_2.jpg?rlkey=fjq3a9re53cv5l0zn9ya00akk&raw=1
It would be used in development and production test. Every
RP2040-based board would have the small-pitch 20 pin ribbon cable
header.
The pushbuttons look primitive but will probably work.
On 2024-01-16, john larkin <jl@650pot.com> wrote:
This is a first pass at the dev board.
https://www.dropbox.com/scl/fi/709v4pqjhe91jnwqh4wvg/Z566_Sch_2.jpg?rlkey=fjq3a9re53cv5l0zn9ya00akk&raw=1
It would be used in development and production test. Every
RP2040-based board would have the small-pitch 20 pin ribbon cable
header.
Those are huge. For SWD, I really like the 10-pin Cortex-Debug connectors >(1.27mm pitch). Or a minimal 2*3 pin 2.54mm header.
The pushbuttons look primitive but will probably work.
What are these for? I would wire a BSS138 to a free GPIO to automate that. >However, when using SWD, you should not really need them.
cu
Michael
On Tuesday, January 16, 2024 at 11:02:40?AM UTC-8, john larkin wrote:
This is a first pass at the dev board.
https://www.dropbox.com/scl/fi/709v4pqjhe91jnwqh4wvg/Z566_Sch_2.jpg?rlkey=fjq3a9re53cv5l0zn9ya00akk&raw=1
It would be used in development and production test. Every
RP2040-based board would have the small-pitch 20 pin ribbon cable
header.
Why bother with pins, and ribbon connector insertion force? Just print
test point pads, a few alignment holes, and make a plug of
spring pins. It's not like you need this access while the unit is
bolted into its box and racked into a larger system.
Do it with two different diameter alignment pins, so it doesn't get
reversed. A captive nut to retain it would be useful, too.
Why bother with pins, and ribbon connector insertion force? Just print
test point pads, a few alignment holes, and make a plug of
spring pins. It's not like you need this access while the unit is
bolted into its box and racked into a larger system.
Do it with two different diameter alignment pins, so it doesn't get
reversed. A captive nut to retain it would be useful, too.
Those are huge. For SWD, I really like the 10-pin Cortex-Debug connectors >>(1.27mm pitch). Or a minimal 2*3 pin 2.54mm header.
The half-pitch 20 wire ribbon cable is just 0.5" wide. The box
connector on the target board is just a bit wider. That's not bad.
I plan to use all 20 wires, so I can do the CPU debug and check power supplies and clocks and stuff, and snoop code execution times.
What are these for? I would wire a BSS138 to a free GPIO to automate that. >>However, when using SWD, you should not really need them.
Pushing the buttons can set the 2040 into USB memory-stick mode, to
access the flash. That could be handy.
I think I'll do both, allow the buttons and a couple of Pi400 port
pins to ground RUN and BOOT.
Do you know if there is a way for running software to essentialy reset
itself and enter the USB flash-stick mode? That could be handy for
field code upgrades.
On Wed, 17 Jan 2024 12:16:29 -0800 (PST), whit3rd <whit3rd@gmail.com>
wrote:
On Tuesday, January 16, 2024 at 11:02:40?AM UTC-8, john larkin wrote:
This is a first pass at the dev board.
https://www.dropbox.com/scl/fi/709v4pqjhe91jnwqh4wvg/Z566_Sch_2.jpg?rlkey=fjq3a9re53cv5l0zn9ya00akk&raw=1
It would be used in development and production test. Every
RP2040-based board would have the small-pitch 20 pin ribbon cable
header.
Why bother with pins, and ribbon connector insertion force? Just print >>test point pads, a few alignment holes, and make a plug of
spring pins. It's not like you need this access while the unit is
bolted into its box and racked into a larger system.
Do it with two different diameter alignment pins, so it doesn't get >>reversed. A captive nut to retain it would be useful, too.
Too much work! We can buy the ribbon cables and connectors from
stock.
On 2024-01-18, john larkin <jl@650pot.com> wrote:
On Wed, 17 Jan 2024 12:16:29 -0800 (PST), whit3rd <whit3rd@gmail.com>
wrote:
On Tuesday, January 16, 2024 at 11:02:40?AM UTC-8, john larkin wrote:
This is a first pass at the dev board.
https://www.dropbox.com/scl/fi/709v4pqjhe91jnwqh4wvg/Z566_Sch_2.jpg?rlkey=fjq3a9re53cv5l0zn9ya00akk&raw=1
It would be used in development and production test. Every
RP2040-based board would have the small-pitch 20 pin ribbon cable
header.
Why bother with pins, and ribbon connector insertion force? Just print >>>test point pads, a few alignment holes, and make a plug of
spring pins. It's not like you need this access while the unit is >>>bolted into its box and racked into a larger system.
Do it with two different diameter alignment pins, so it doesn't get >>>reversed. A captive nut to retain it would be useful, too.
Too much work! We can buy the ribbon cables and connectors from
stock.
True, you'd have to order from digikey and wait a day to get such a
connector (tag connect)
we use the Tag Connect TC2030IDC connector intended for PIC programming to >program our ESP32 boards one end plugs right into the ESP-prog, no >modification is needed.
The price seems to have dropped recently, perhaps a patent has
expired, also I'm seeing Chinese clones now.
On 2024-01-18, john larkin <jl@650pot.com> wrote:
On Wed, 17 Jan 2024 12:16:29 -0800 (PST), whit3rd <whit3rd@gmail.com>
wrote:
On Tuesday, January 16, 2024 at 11:02:40?AM UTC-8, john larkin wrote:
This is a first pass at the dev board.
https://www.dropbox.com/scl/fi/709v4pqjhe91jnwqh4wvg/Z566_Sch_2.jpg?rlkey=fjq3a9re53cv5l0zn9ya00akk&raw=1
It would be used in development and production test. Every
RP2040-based board would have the small-pitch 20 pin ribbon cable
header.
Why bother with pins, and ribbon connector insertion force? Just print >>>test point pads, a few alignment holes, and make a plug of
spring pins. It's not like you need this access while the unit is >>>bolted into its box and racked into a larger system.
Do it with two different diameter alignment pins, so it doesn't get >>>reversed. A captive nut to retain it would be useful, too.
Too much work! We can buy the ribbon cables and connectors from
stock.
True, you'd have to order from digikey and wait a day to get such a
connector (tag connect)
we use the Tag Connect TC2030IDC connector intended for PIC programming to >program our ESP32 boards one end plugs right into the ESP-prog, no >modification is needed.
The price seems to have dropped recently, perhaps a patent has
expired, also I'm seeing Chinese clones now.
On Sat, 9 Mar 2024 01:26:48 -0000 (UTC), Jasen Betts
<usenet@revmaps.no-ip.org> wrote:
On 2024-01-18, john larkin <jl@650pot.com> wrote:
On Wed, 17 Jan 2024 12:16:29 -0800 (PST), whit3rd <whit3rd@gmail.com>
wrote:
On Tuesday, January 16, 2024 at 11:02:40?AM UTC-8, john larkin wrote:
This is a first pass at the dev board.
https://www.dropbox.com/scl/fi/709v4pqjhe91jnwqh4wvg/Z566_Sch_2.jpg?rlkey=fjq3a9re53cv5l0zn9ya00akk&raw=1
It would be used in development and production test. Every
RP2040-based board would have the small-pitch 20 pin ribbon cable
header.
Why bother with pins, and ribbon connector insertion force? Just print >>>>test point pads, a few alignment holes, and make a plug of
spring pins. It's not like you need this access while the unit is >>>>bolted into its box and racked into a larger system.
Do it with two different diameter alignment pins, so it doesn't get >>>>reversed. A captive nut to retain it would be useful, too.
Too much work! We can buy the ribbon cables and connectors from
stock.
True, you'd have to order from digikey and wait a day to get such a >>connector (tag connect)
we use the Tag Connect TC2030IDC connector intended for PIC programming to >>program our ESP32 boards one end plugs right into the ESP-prog, no >>modification is needed.
The price seems to have dropped recently, perhaps a patent has
expired, also I'm seeing Chinese clones now.
Why do many of the target PCBs have four additional giant holes?
On 2024-03-09, John Larkin <jl@997PotHill.com> wrote:
On Sat, 9 Mar 2024 01:26:48 -0000 (UTC), Jasen Betts >><usenet@revmaps.no-ip.org> wrote:
On 2024-01-18, john larkin <jl@650pot.com> wrote:
On Wed, 17 Jan 2024 12:16:29 -0800 (PST), whit3rd <whit3rd@gmail.com>
wrote:
On Tuesday, January 16, 2024 at 11:02:40?AM UTC-8, john larkin wrote: >>>>>
This is a first pass at the dev board.
https://www.dropbox.com/scl/fi/709v4pqjhe91jnwqh4wvg/Z566_Sch_2.jpg?rlkey=fjq3a9re53cv5l0zn9ya00akk&raw=1
It would be used in development and production test. Every
RP2040-based board would have the small-pitch 20 pin ribbon cable
header.
Why bother with pins, and ribbon connector insertion force? Just print >>>>>test point pads, a few alignment holes, and make a plug of
spring pins. It's not like you need this access while the unit is >>>>>bolted into its box and racked into a larger system.
Do it with two different diameter alignment pins, so it doesn't get >>>>>reversed. A captive nut to retain it would be useful, too.
Too much work! We can buy the ribbon cables and connectors from
stock.
True, you'd have to order from digikey and wait a day to get such a >>>connector (tag connect)
we use the Tag Connect TC2030IDC connector intended for PIC programming to >>>program our ESP32 boards one end plugs right into the ESP-prog, no >>>modification is needed.
The price seems to have dropped recently, perhaps a patent has
expired, also I'm seeing Chinese clones now.
Why do many of the target PCBs have four additional giant holes?
For the retaining hooks, AKA "legs", these are optional.
On Sat, 9 Mar 2024 19:51:58 -0000 (UTC), Jasen Betts
<usenet@revmaps.no-ip.org> wrote:
On 2024-03-09, John Larkin <jl@997PotHill.com> wrote:
On Sat, 9 Mar 2024 01:26:48 -0000 (UTC), Jasen Betts >>><usenet@revmaps.no-ip.org> wrote:
Why do many of the target PCBs have four additional giant holes?
For the retaining hooks, AKA "legs", these are optional.
I think they are some sorts of stabilizers; must make the connections
more reliable.
They really blow up the board area. I like my 20-pin
ribbon connector better.
I can sneak the ribbon cable out of a closed box, for temperature
testing or whatever. And bring out more signals. That pogo thing
sticks up.
On 2024-03-09, John Larkin <jl@997PotHill.com> wrote:
On Sat, 9 Mar 2024 19:51:58 -0000 (UTC), Jasen Betts >><usenet@revmaps.no-ip.org> wrote:
On 2024-03-09, John Larkin <jl@997PotHill.com> wrote:
On Sat, 9 Mar 2024 01:26:48 -0000 (UTC), Jasen Betts >>>><usenet@revmaps.no-ip.org> wrote:
Why do many of the target PCBs have four additional giant holes?
For the retaining hooks, AKA "legs", these are optional.
I think they are some sorts of stabilizers; must make the connections
more reliable.
They are plastic hooks they make the connection more reliable by
maintaining it hands-free. Without them you must hold the connector
to the board fighting the spring force of the pogo-pins.
They really blow up the board area. I like my 20-pin
ribbon connector better.
Yes.
I can sneak the ribbon cable out of a closed box, for temperature
testing or whatever. And bring out more signals. That pogo thing
sticks up.
It seems unsuited for your application.
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