unusual bare metal target: Amazon Dash

[Laeeth Isharc via Digitalmars-d-learn]

On Tuesday, 18 August 2015 at 04:36:49 UTC, Rikki Cattermole 
wrote:
> On 18/08/2015 1:32 p.m., Laeeth Isharc wrote:
>> I don't know whether D can run on one, but from a quick look 
>> perhaps
>> feasible.  Running D on something like this (perhaps it's 
>> underpowered,
>> but looked to have similar spec to what people had been doing 
>> with
>> related ARM cortex processors) would certainly make the point 
>> very vivid
>> that it can be a bare metal programming language.
>>
>> Only 1Mb of flash RAM for the program - is that enough?
>>
>> https://learn.adafruit.com/dash-hacking-bare-metal-stm32-programming/programming
>>
>> https://learn.adafruit.com/dash-hacking-bare-metal-stm32-programming/overview
>>
>>
>> The Amazon Dash button is a tiny device that orders products 
>> from
>> Amazon.com at the press of a button.  It's designed to be put 
>> wherever
>> you store consumeables like paper towels, trash bags, etc. so 
>> that you
>> can easily order more when they run out.  The Dash is great at 
>> what it's
>> designed to do, but did you know inside the Dash is a powerful 
>> ARM
>> Cortex-M3 processor and WiFi module that are very similar to 
>> wireless
>> development boards like the Particle Photon?  You'll even find 
>> there are
>> easily accessible test pads on the Dash which allow you to 
>> reprogram its
>> CPU and turn it into your own $5 internet button!  This guide 
>> will
>> explore how to take apart the Dash and reprogram its CPU to 
>> run your own
>> code.
>> ...
>> The CPU is a STM32F205RG6 processor which is an ARM Cortex-M3 
>> that can
>> run up to 120mhz and has 128 kilobytes of RAM and 1 megabyte 
>> of flash
>> memory for program storage.
>> The WiFi module is a BCM943362 module which in combination 
>> with the CPU
>> make it a platform for Broadcom's WICED SDK.
>> There's a 16 megabit SPI flash ROM which is typically used in
>> conjunction with the WICED SDK for storing application data.
>> An ADMP441 microphone is connected to the CPU and used by the 
>> Dash iOS
>> application to configure the device using the speaker on a 
>> phone/tablet.
>> There's a single RGB LED and a button.
>
> By what you are saying, I believe it should be doable.
> Although I'm a little worried for the WiFi support. Do you need 
> to include the code to drive it beyond wrap up some 
> communication to it?
>
> 1mb flash should be enough to run D code on it. If you strip 
> out a good percentage of druntime and definitely no Phobos.
> Although you may be able to mark and use some of that 16mb 
> flash rom as executable code storage. If that's so, you'll be 
> in a good place to have more then 1mb. It would require some 
> clever runtime linking tricks however.
>
> I'm probably not the best person to go more in depth about it 
> or the specific chips. So I won't. Most of my knowledge comes 
> from reading what others says and talking with Jens Bauer.

I think its doable too.  Nobody seems to have figured out the 
wifi yet - more at LED flashing stage.   It's funny these wifi 
devices have microphones in them !