Re: Emulation of IOT hardware

[Philippe Mathieu-Daudé]

On 9/28/21 15:04, Alex Bennée wrote:
> 
> Niraj Sorathiya <nirajsorathiya101@gmail.com> writes:
> 
>> Hello Team,
>>
>> Would you please give me some suggestions on how I should proceed to
>> build an IOT (Internet of Things) emulator ?
> 
> Maybe look at the Musca boards:
> 
>   https://qemu.readthedocs.io/en/latest/system/arm/musca.html
> 
> these are based ARM's IoTKit which are modern ARM M-profile boards for IoT 
> development.
> 
>> What aspects do I
>> need to consider ?  IOT can be anything like a smart light ,smart bulb 
>> ,smart lock ,etc. Here smart means that the device can be controlled
>> via the internet.
> 
> It really depends on what you are interested in modelling?
> 
> One area where we currently fall down is how we handle GPIO type setups
> in emulation. While we have models for displays and backends for network
> and block devices we haven't got coherent way to represent (and change)
> arbitrary IO pins. 

You can use LEDs as a starting point, see commit 7cfbde5ea1c
("hw/arm/aspeed: Add the 3 front LEDs drived by the PCA9552 #1"):

    The Witherspoon has 3 LEDs connected to a PCA9552. Add them.
    The names and reset values are taken from:

https://github.com/open-power/witherspoon-xml/blob/master/witherspoon.xml

    Example booting obmc-phosphor-image:

      $ qemu-system-arm -M witherspoon-bmc -trace led_change_intensity
      1592693373.997015:led_change_intensity LED desc:'front-fault-4'
color:green intensity 0% -> 100%
      1592693373.997632:led_change_intensity LED desc:'front-power-3'
color:green intensity 0% -> 100%
      1592693373.998239:led_change_intensity LED desc:'front-id-5'
color:green intensity 0% -> 100%
      1592693500.291805:led_change_intensity LED desc:'front-power-3'
color:green intensity 100% -> 0%
      1592693500.312041:led_change_intensity LED desc:'front-power-3'
color:green intensity 0% -> 100%
      1592693500.821254:led_change_intensity LED desc:'front-power-3'
color:green intensity 100% -> 0%
      1592693501.331517:led_change_intensity LED desc:'front-power-3'
color:green intensity 0% -> 100%
      1592693501.841367:led_change_intensity LED desc:'front-power-3'
color:green intensity 100% -> 0%
      1592693502.350839:led_change_intensity LED desc:'front-power-3'
color:green intensity 0% -> 100%
      1592693502.861134:led_change_intensity LED desc:'front-power-3'
color:green intensity 100% -> 0%
      1592693503.371090:led_change_intensity LED desc:'front-power-3'
color:green intensity 0% -> 100%

    We notice the front-power LED starts to blink at a ~2Hz rate.

Regards,

Phil.