[Tinkerphones] Mikrophone

[Paul Boddie]

Hello,

Here's another phone project, one funded by NLnet, that attempts to partition 
functionality between different units:

https://mikrophone.net/
https://nlnet.nl/project/mikroPhone/

Unlike various "privacy-enhanced" products seen previously, however, this one 
separates core telephony from smartphone functionality, as opposed to trying 
to control (or simply disconnect) smartphone access to the network. There are 
still some familiar characteristics, like the separate cellular modem (in the 
form of the popular SIMCom and Quectel modules) and the use of a dedicated 
microcontroller for some aspects of the device.

Unlike other designs where the microcontroller does some kind of bootstrapping 
exercise related to privacy or "purity", or where mundane functions have been 
delegated to it, here it is apparently providing a featurephone environment. 
Indeed, there are two microcontrollers: a primary RISC-V device and a 
secondary ESP32 device for Wi-Fi and Bluetooth. See this repository directory 
for an indication of what is going on in the primary microcontroller:

https://git.majstor.org/mikroPhone/tree/fw/fe310/phone

For the smartphone functionality, it appears that the project is going to 
follow the lead of other designs and use an i.MX 8M device. This is supposedly 
going to run Linux or Android, and it seems that the idea is to give only the 
microcontroller or the smartphone functionality access to the screen, keypad 
and communications facilities at any given time.

Obviously, a single SoC could provide partitioned environments for core 
telephony and smartphone functionality, with less powerful cores even doing 
the work of microcontrollers if appropriate. Using an SoC-level device would 
probably make the core functionality easier to develop and more comprehensive, 
as well as being more easily extensible. But perhaps the core functionality is 
regarded as something that does not need to be developed further or, indeed, 
be much more than what we were all using back in the glory days of Nokia and 
Ericsson.

Anyway, it hopefully provides an opportunity to reflect on the way these kinds 
of products are designed and the choices their designers have made.

Paul