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:
>>
>>>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.

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.

--
Jasen.
🇺🇦 Слава Україні

On Mon, 11 Mar 2024 05:38:52 -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 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.

The real advantage of the pogo thing is its small cost saving, which
matters in high-volume, low margin products.

In high volume, one could both JTAG and access all the other signals
(like the ones I want) with a whole-board pogo fixture, but that has
downsides too.