Hi! Thanks for the interest in CircuitPython. I've answered each of your questions below.
I also want to remind folks that Teensy support isn't a focus for Adafruit folks who work on CircuitPython. The features we add for the iMX RT benefit Teensy but aren't driven by the goal of supporting Teensy. We'd love contributions for these things though. It's just not a priority for us.
Different flash sizes are easy to support and should already work.
All pins should just work. When we add support for an MCU we add all pins on it regardless of what is broken out on the board. The only board specific pin support is the name mapping made available in the `board` module. We do end up finding some data copy issues for pins that haven't been tested. These bugs are somewhat rare and easy to fix when we find them.
We currently support SD cards with a Python library: https://github.com/adafruit/Adafruit_CircuitPython_SD/ This will work on any board with SPI support on SD card pins. Jeff (jepler) is also actively working on native SD card support (both SPI and SDIO) for STM and SAMD51 I believe. This will make it easier to support on iMX because the APIs will be established already. However, I don't know if adding iMX RT support is planned.
We don't have any immediate plans to support additional RAM or FLASH. It should be usable over the SPI connection but not natively.
This would depend on USB host support for iMX RT in TinyUSB and also establishing USB host APIs in CircuitPython. It is something we'd like to do at some point but it's not something we plan to do soon.
We don't have plans to add support for this. We have "native" support for WizNet but we'll likely deprecate it. Most of our network support is from Python-only and I'd like us to have a better API that handles Python support primarily and then fits native into that. We'll be evolving the APIs for this with the ESP32S2 WiFi support that is upcoming and a priority.
Hope that gives some insight into our priorities! As always, we'd love more contributors to CircuitPython and are always happy to help get folks working on CircuitPython. These priorities are for those of us sponsored by Adafruit.
I also want to remind folks that Teensy support isn't a focus for Adafruit folks who work on CircuitPython. The features we add for the iMX RT benefit Teensy but aren't driven by the goal of supporting Teensy. We'd love contributions for these things though. It's just not a priority for us.
I don't yet have a Teensy 4.1, just Teensy 4.0.
Any new feature of Teensy 4.1 (with respect Teensy 4.0) is implemented in CircuitPython 5.4.0-beta.0 for Teensy 4.1 ?
- internal 8MB flash memory seems recognized, with 7MB as file system, from post #93;
Different flash sizes are easy to support and should already work.
- all additional pins (to be confirmed);
All pins should just work. When we add support for an MCU we add all pins on it regardless of what is broken out on the board. The only board specific pin support is the name mapping made available in the `board` module. We do end up finding some data copy issues for pins that haven't been tested. These bugs are somewhat rare and easy to fix when we find them.
- microSD (most important feature, IMHO) ?
We currently support SD cards with a Python library: https://github.com/adafruit/Adafruit_CircuitPython_SD/ This will work on any board with SPI support on SD card pins. Jeff (jepler) is also actively working on native SD card support (both SPI and SDIO) for STM and SAMD51 I believe. This will make it easier to support on iMX because the APIs will be established already. However, I don't know if adding iMX RT support is planned.
- QSPI Memory via external PSRAM and/or flash chips ?
We don't have any immediate plans to support additional RAM or FLASH. It should be usable over the SPI connection but not natively.
- USB host via Teensy 4.1's USB Host port ?
This would depend on USB host support for iMX RT in TinyUSB and also establishing USB host APIs in CircuitPython. It is something we'd like to do at some point but it's not something we plan to do soon.
- Ethernet network via 10/100 Mbit Ethernet PHY ?
We don't have plans to add support for this. We have "native" support for WizNet but we'll likely deprecate it. Most of our network support is from Python-only and I'd like us to have a better API that handles Python support primarily and then fits native into that. We'll be evolving the APIs for this with the ESP32S2 WiFi support that is upcoming and a priority.
Hope that gives some insight into our priorities! As always, we'd love more contributors to CircuitPython and are always happy to help get folks working on CircuitPython. These priorities are for those of us sponsored by Adafruit.