One of the Band switching outputs available on the Langstone is GPIO Pin 28. On the Raspberry Pi 4, GPIO pins 27 and 28 are reserved for the EEPROM associated with Raspberry Pi "HATs".
I have found that if some switching modules are connected to pin 28, newly-imaged Raspios SD cards will not boot and will freeze at the Rainbow screen.
The Pin allocation table for the Portsdown 4 will be modified to avoid these pins. More news to come.
Dave, G8GKQ
Don't Connect Anything to GPIO Pins 27 and 28
Re: Don't Connect Anything to GPIO Pins 27 and 28
Thanks Dave,
When you decide which pin you are using for Portsdown I will change Langstone to be the same.
Colin.
When you decide which pin you are using for Portsdown I will change Langstone to be the same.
Colin.
Re: Don't Connect Anything to GPIO Pins 27 and 28
Oh dear. I think I already have...G8GKQ wrote: ↑Fri Sep 11, 2020 3:58 pmOne of the Band switching outputs available on the Langstone is GPIO Pin 28. On the Raspberry Pi 4, GPIO pins 27 and 28 are reserved for the EEPROM associated with Raspberry Pi "HATs".
I have found that if some switching modules are connected to pin 28, newly-imaged Raspios SD cards will not boot and will freeze at the Rainbow screen.
The Pin allocation table for the Portsdown 4 will be modified to avoid these pins. More news to come.
Dave, G8GKQ
Re: Don't Connect Anything to GPIO Pins 27 and 28
I have an Arduino monitoring pin 28 but have had no boot-up issues with that - unless it's causing that strange IP effect Dave?
73, Martin - G4FKK
73, Martin - G4FKK
Re: Don't Connect Anything to GPIO Pins 27 and 28
Probably just a firmware boot from EPROM option someone over at the developers unilaterally decided to change one day. to test their widget without telling everyone else or forgetting to change it back... hopefully it can be disabled. PIN28 has relay 1 on it in the Langstone. It's worked fine up to now so hopefully it will work again.
Mike
Mike
Re: Don't Connect Anything to GPIO Pins 27 and 28
To retain compatibility with existing systems I will probably just duplicate those two pins with two new ones. If existing systems work OK then they will continue to do so. If people have boot hangups they can use the two new pins instead.
Re: Don't Connect Anything to GPIO Pins 27 and 28
In the next Portsdown 4 software update, I will move Band D0, which was on GPIO physical pin 28, to be output on GPIO pin 32. It would make sense to move the Langstone Band D7 output to the same pin - thanks Colin.
This change will leave GPIO pins 27 and 28 with no connection as recommended by the Raspberry Pi foundation.
The issue appeared to be that these pins are used for i2c signalling (with a potential Raspberry Pi HAT) during the early stages of the boot process of a brand new SD Card, and the boot would hang if the load on one of the pins was too high to enable it to reach the Logic high threshold within the i2c signalling specification.
SD Cards that had already been built as Portsdown or Langstone cards seemed to skip this step and were not affected by the issue.
Dave, G8GKQ
This change will leave GPIO pins 27 and 28 with no connection as recommended by the Raspberry Pi foundation.
The issue appeared to be that these pins are used for i2c signalling (with a potential Raspberry Pi HAT) during the early stages of the boot process of a brand new SD Card, and the boot would hang if the load on one of the pins was too high to enable it to reach the Logic high threshold within the i2c signalling specification.
SD Cards that had already been built as Portsdown or Langstone cards seemed to skip this step and were not affected by the issue.
Dave, G8GKQ