[Ovmsdev] OVMS v3

[Mark Webb-Johnson]

Marcos,

Looks really interesting as a form factor.

I looked at both Pi and BeagleBone black for this project, but power requirements are very high for both. The modules are both designed for 3G graphics via HDMI, don’t have CAN bus, and probably have too high CPU speed and RAM+Flash for our needs. Really not a good fit from what I can see (excessive in some areas, not enough in others), but the Raspberry Compute Module is a lot closer than the original Pi A. It seems to be that using the older A version of the Pi, and re-working the power supply, 20% can be saved on the power, but that is still no-where close to what we want. I saw another product where they paired a little arduino MCU beside the Pi, to be able to sleep/awake the Pi and reduce power consumption.

From a power point of view, the only way this is going to work if we are going to be able to put as much as possible to sleep when the car is not driving and not charging, but to be able to wake it up remotely from the App if necessary. It seems that using a smart modem should give us that capability - as we can control GPIOs from the modem and have that wake up the CPU if necessary.

Regards, Mark.

On 21 Jun, 2014, at 4:59 am, Marcos Mezo <mmezo at selexco.net> wrote:

> Hello everyone,
> 
> no really knowing at all about all this, but... Have you heard about the Raspberry Compute Module?
> 
> It's basically the Raspberry A on a module + 4Gb Flash. I think it's design is open and the page says it will sell for about 30$ in batches of 100, a bit more for individual purchases. It has internal 4Gb Flash and 512Mb RAM and a 32bit CPU ). All the gpios and everything else are routed to a SODIMM connector.
> 
> I've read in the product documentation [2] that internally, the broadcom chip does not power at all it's different parts or modules unless they are beeing used, so if no 3D is used this part of the chip is not powered and draining any power...
> 
> Theres is still no CAN or Wifi or bluetooth, but maybe that could be in the "mainboard". There could even be different mainboards with/without Wifi or 3g... 
> 
> Just my 2c in case it can be useful.
> 
> [1] http://www.raspberrypi.org/raspberry-pi-compute-module-new-product/
> [2] http://www.raspberrypi.org/documentation/hardware/computemodule/README.md
> 
> Marcos
> 
>> For me, the requirement comes down to a base framework and module that supports:
>> 32bit CPU with enough grunt, and a low-power sleep mode
>> Dual CAN
>> Async + I2C + SPI + GPIO expansion
>> SD-Card
>> USB
>> Lots of RAM and FLASH
>> Wifi
>> Bluetooth
>> Optional GSM
>> Optional display (or can we get away with bluetooth to a cellphone?)
>> 
>> What is interesting is the advent of low-cost Linux frameworks that are very close to what we need. Things like the BeagleBone and RasberryPi are fascinating, but really designed for HDMI video output - and the overhead of GPU + HDMI is a huge power drain. The closest I've found to what we require is (http://compulab.co.il/products/computer-on-modules/cm-t335/) - pretty amazing little device - low power, wifi+bluetooth, dual CAN, up to 512MB RAM and 1GB FLASH, for around US$50 (in horrendous quantities). I'm working with my contacts in China to see if we can base on a dev board something like that. If they can make Android phones for US$50, we should be able to get the guts of such a device for something similar. Then, add on GSM, take it from a BOM to a product, and we're probably looking at something still <US$150 but with so much more. The closest thing to ideal I've found at the moment is build a baseboard (connectors, power, CAN buses, etc) and have slots to take that CM-T335 module and an optional GSM module. But, I still think we can find something on the China market even closer to what we want/need.
> 
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