LinkIt Smart 7688 Duo


 
So technically, if we could get the code to work (by we, I mean you and Bryan), then we could design a new board foregoing the ATMEGA components and provide a plug in interface with the board. Sounds like a win-win to me.

So Bryan, you'll have this ready to go tomorrow?
 
Yeah, at first glance it looks like it should be able to replace the RasPi + ATMEGA components. Most of the components on the HM board would still remain (power, voltage regulation, input filtering, blower and servo output, etc). It would certainly reduce the overall footprint of the HeaterMeter and the size of case required.
 
These sort of things pop up all the time, but this one is pretty well done. The ATmega only costs about $2 so there's not much savings there, but the integrated host system knocks about $20 off the cost of a HeaterMeter. One problem I see right off the bat is that the atmega is only run at 8MHz. A lot of the fun things HeaterMeter does is sort of time-sensitive, like servo control and a freerunning ADC, so it could produce a worse experience than the 16MHz version when ever line of code takes twice as long to execute, and the big ADC interrupt handler starts eating all the clock cycles.

Still, I'll put it on my list to possibly check out if nothing else comes out between then and now!
 
Placed an order for one of the duo units. Once it arrives in 15-700 business days, I'll give the OpenWRT side of things a shot. MediaTek looks to have a well maintained github repo for it.
 
Yeah theoretically if they run off the mainline OpenWrt, you should just be able to build linkmeter for that target, which only really requires rrdtool which should build as well?
 
Looks like a nice board for current code....

I'm getting 'excited' about the new esp32

With all that goodness in one chip it looks like it could be a nice solution for a 'future' port/version (atmega is getting pretty limiting now).....trying to get one asap....
 
The ESP32 is pretty sweet, I do love the ESP8266es I have here. They're great to whip up a quick sensor + MQTT publisher. With the new dual core, you never have to worry about starving the wifi of CPU cycles and causing it to drop off. However, I don't think it will ever have enough power to run LinkMeter just because you need to have a database at the very least and it isn't really beefy enough to do an RRD, the file would take all the RAM so you'd need to be constantly swapping out chuncks of it to flash. Then you need to also do email and push notifications and you're already out of space. Still, it is pretty awesome and it has other IoT uses.

Looking at the LinkIt Smart 7688 without the atmega onboard, the pinout is way different, and the SPI bus connects to flash so you can't really use that to program the atmega like they doing (and we're doing). Checking the OpenWrt source looks like they've got it in Trunk (although they no longer have a profile for the LinkIt specifically, it appears to be handled by the "default" profile). Should be straight forward if it works, the only real question then is the ATmega at 8MHz.
 
Yeah you can just set the clock multiplier in setup() to div/2 and recompile everything with F_CPU set to 8000000
Code:
    CLKPR = bit(CLKPCE);
    CLKPR = 1;
 
The ESP32 is pretty sweet, I do love the ESP8266es I have here. They're great to whip up a quick sensor + MQTT publisher. With the new dual core, you never have to worry about starving the wifi of CPU cycles and causing it to drop off. However, I don't think it will ever have enough power to run LinkMeter just because you need to have a database at the very least and it isn't really beefy enough to do an RRD, the file would take all the RAM so you'd need to be constantly swapping out chuncks of it to flash. Then you need to also do email and push notifications and you're already out of space. Still, it is pretty awesome and it has other IoT uses.

yeah, I keep on 'forgetting' about LinkMeter, as I don't use it. I've been using the Esp8266-Thingspeak route for over 20 cooks so far and it works great for me(I think I'm the only one using it). The esp32 modules should come with 16MB external flash (8266 are now that size) so it should be enough space to store info for a 'stand-alone' type linkmeter-clone....but I still like the cloud storage as it keeps the HM device pretty 'simple'.
 
yeah, I keep on 'forgetting' about LinkMeter, as I don't use it. I've been using the Esp8266-Thingspeak route for over 20 cooks so far and it works great for me(I think I'm the only one using it). The esp32 modules should come with 16MB external flash (8266 are now that size) so it should be enough space to store info for a 'stand-alone' type linkmeter-clone....but I still like the cloud storage as it keeps the HM device pretty 'simple'.

David, I used my ESP setup on my last cook. Love it.
 
What about using an 8mhz oscillator to do it via hardware?
I think you can just set the fuses to use the internal oscillator, but I've never tried and I know know what happens if you have an external oscillator at the same time. You definitely could do it if you swapped the part out, but you'd still need to recompile heatermeter with the new F_CPU so might as well just do it in software with the divider.
 
Should be easy enough to test the current HM board at 8Mhz, no?

FYI....I've got an 8Mhz arduino pro mini 3.3v board working with HM code(well my personal 'slim-downed' fork of the HM code) on a test bed. It controls servo/fan with no issues that I can see. I didn't change anything with timing/cpuclock with the HM code. I don't know about the ADC because I'm using SPI/Max6675 for temperature readings....also don't use the LCD/buttons....just headless;
 

 

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