Portsdown default I2C and use of GPIO 14/15

[G8PUO]

Hi, looking at understanding the various GPIOs that Portsdown uses, in particular for use for the repeater.

Not knowing the history of why the I2C was moved/duplicated from the default Pi GPIO 2/3 to GPIO 14/15, was it only relating to separating RTC, or for higher clock speeds for the ADF5355?

https://wiki.batc.org.uk/DATV_Repeater_i2c_Interface

Could not find anything that jumped out relating to Portsdown 4, so any info would be appreciated.

Have created a matrix of the Pi4 and Portsdown 4 connections. This is WIP and helps me have a holistic overview.

Thanks
Dave

[G8GKQ]

Hi Dave

Not quite sure what the point of your exercise is here. You seem to be comparing apples with oranges.

The DATV Repeater Controller and the Portsdown are 2 totally separate projects; you can't run them both on the same physical Raspberry Pi. It is not even possible to have a test rig that copes with both configurations (I did try once).

The Portsdown 4 GPIO usage is non-standard as it evolved from the Portsdown 2020 which in turn evolved from some very early work by F5OEO and myself (when I really did not understand enough about it!). It has since been modified slightly for compatibility with the Langstone transceiver.

The Repeater Controller GPIO usage was a fresh start, trying to learn from the mistakes that I had made during Portsdown 2020/4 development, so it more closely mirrors the Raspberry Pi foundation's recommendations on pin usage.

Maybe I've misunderstood your question, but hopefully I've managed to explain why we are where we are.

73

Dave

[G8PUO]

Hi Dave,

Really appreciate your reply and information.

Background
As a 'newcomer' to Portsdown (although did dabble slightly a few years ago), my objective was to get an idea of what the GPIOs offered for the repeater controller - this then led to the two exposed I2C ports.

In order to try understand, I am pulling the matrix together of all the GPIO info I could glean from the Wiki's, together with odd comments on various pages, and this hopefully expand in detail and give me a holistic overview - AKA picture in my mind of potential connections and what I could do and equally can not do.

Also respect that the project has evolved massively over the years and gallons of midnight oil has been consumed in the process - which is genuinely appreciated by many.

Evaluation
Will now wander off, install and explore the repeater controller build, play and learn more in the lab - also about overall power management. I would like to embrace this route for both repeaters but importantly build reliability confidence out in the field, when for example a power outage may regularly happen (particularly on FW which is totally solar/wind/battery powered) and ensure the Pi services and repeater always recovers in the right state.

Thank you
KR Dave

[g8lce]

A pico can be used as a repeater controller which may not worry so much about power cuts. GB3NQ has one which controls the Ryde selection via a HDMI switch and controls a media player etc. Still early days but moving forward. I am only using the repeater and offering support, testing and videos. The others are programming, mending, visiting the repeater and we are all learning a lot!

Martin G8LCE

[G8PUO]

Many thanks Martin, looks to be an interesting project.

Have made some progress with my logic too, details can be found https://www.hackster.io/DitroniX/batc-r ... sdk-545ba5

The eventual aim is to allow battery backup, as well as control of the repeater logic, HDMI, Audio and watchdog, all on one PiHat - or two stacked.

Like yourself, just not enough hours in the day!