The Signpost platform could be used for the Parking Meter use case. Below are some Signpost-specific notes.

Overview

Looking at TockOS GitHub, it seems that the kernel is in Rust and the userland applications are in C.

So, we could either

Some of the modules will have a Cortex M4 processor, see Duktape Eclipse Setup for how to use Duktape with the Cortex M4.

The master compute module is an Intel Edison, see Services 16-Dec-16 call.

Rust Accessor Host

The Rust Accessor Host (Rusteduk) binaries are rather larger, will they fit in 256K or 512K along with the TockOS kernel?

The Duktape Accessor Host binaries are rather larger, will they fit in 256K or 512K along with the TockOS kernel?

For protoptyping, we would like a Cortex M4 with 512K of memory.
- Cortex M4 because that is what Duktape Eclipse ARM Cortex M4

512K of memory so that we have breathing room. 256K might not work. Duktape Eclipse ARM Cortex M4 was reported to have the following sizes:
- Code size = 176K
- Constants = 628 bytes
- RAM = 492 bytes

That is getting close to 256K, which is why I think I need 512K

None of the boards listed on the TockOS Github repo are M4 with 512K.
The TockOS Github repo does support the sam4l chip, and there is a M4 512K devel kit available at http://www.atmel.com/tools/ATSAM4L8-XPRO.aspx?tab=overview

The Tock GitHub repo boards/ directory contains directories for the following:

Hail: Our first TockOS Accessor Board, see below
imix - https://www.crowdsupply.com/helena-project/imix - ships February 28. $99 ea. Cortex M4
nrf51dk - Nordicsemi - mouser.com $39: ARM Cortex M0 CPU and 256kB flash and 16kB RAM memory.
storm - "The Firestorm is a platform from UC Berkeley's Software Defined Buildings research group. It is based on the Atmel SAM4L and includes an RF233 802.15.4 radio, a Nordic nRF51822 BLE radio, a light sensor, accelerometer and temperature sensor." http://storm.rocks/: "Storm is a 16mm x 26mm (1/2" by 1") solder on module that combines a 32 bit Cortex M4 microcontroller with an 802.15.4 radio, and 64 Mbit of flash memory" - unclear how to order this

hail "Hail is an embedded IoT module for running Tock. It is programmable over USB, uses BLE for wireless, includes temperature, humidity, and light sensors, and has an onboard accelerometer. Further, it conforms to the Particle Photon form-factor." - Unknown availability. http://lab11.eecs.umich.edu/projects.html does not list it. Brendan has a few. See hail.pptx (account needed) for details.

Hail Board

The Hail Board uses a ATSAM4LC8BA, which has 512K Flash and 64K SRAM.

See TockOS -> Hail for details.

nrf51 - Presumably a Nordicsemi Cortex M0
sam4l - Atmel sam4l Cortex M4 256Kb and 512Kb.
- Atmel SAM4L8 Xplained Pro Evaluation Kit SAM4LC8CA microcontroller: Cortex-M4 with 512KB Flash $56.30 ea.