mike
Thanks for sharing, Josh! It is always fun to see new builds. I'm not familiar with that Freescale part so it will be nice to learn something new. I'm curious about your RFID access board, too (parts, interface?)
I've always hoped that people will interface new controllers with the pykeg core & backend, though so far it hasn't happened; hop onto #kegbot on freenode if you'd like to chat -- I'm usually around on weeknights..
mike
You should definitely look into Freescale. I thought I would never switch from microchip, and was very hesitant. I ended up switching because my senior design project had four stepper motors, so I needed 8 pwm peripherals. Microchip can't satisfy this requirement unless you move to 32 bit which was overkill for my project. Their pulse steering stuff is worthless, as most people generally use a driver chip of some kind and don't need to control all four corners of an h-bridge. In my case, I used TI's SN754410, so I only needed 2 signals per coil.
My dad is a EE and suggested to check out Freescale, and I'm so glad he did! The data sheets are very clear, and all peripheral initialization is done through a GUI in the IDE so you don't need to worry about incorrectly setting a bit and trying to debug the malfunctioning peripheral. Also, the in circuit debugger is cheep ($80), and works for all their processors, except the 32 bit processors. I had some trouble with some of microchips 8 bit processors, specifically the PIC16F1934. I am using it for a prototype MEMS intraoccular pressure sensor and need the 16 channel capacitance module. This processor has been a huge pain- I bought an adapter for the ICD2 because apparently not all PICs program at the same voltage. This still didn't work, apparently its max supply voltage is 4, not the typical 5, so I was burning the chip. Basically what I'm getting at is that Freescale's continuity is a breath of fresh air. Also, National Instruments (LabVIEW) uses Freescale, so that should speak for their exceptional quality. Freescale also has some hybrid chips, with say an H-bridge ASIC and a micro-controller ASIC all in one package.
For the RFID board, the reader/antenna is Innovations ID-12, its I think $25 bucks, very compact compared to Parallax. Uses a serial interface, I think max BR of 9600bps. Sparkfun did a review of this series if you want to check it out. On the board I also have an LED and buzzer, driven by a n channel mosfet.
As for connectivity, there's one USB port on the main board that connects to a host PC that will upload the status to my website using the USB 2.0 peripheral of the MC9S08JM16. I haven't determined if I want to rely on the host computer for authentication or store RFID numbers in the EEPROM. Probably will do it with the EEPROM. The second USB port isn't USB at all, the pinout is as as follows- 1- 5V supply 2-Interrupt from flowmeter 3-Tx from connector on RFID board 4- Voltage divider sense from 1N4148 to INA for temperature measurement 5- GND
As for interfacing it with your backend- I had no plans to do it, I was just going to write my own software on the host computer. Maybe I should look into yours, could save me some time.
Enjoy!
What calibration factors have you all used? Default out of the box for water is something like 6k pulses per liter of water.. And how much of an effect does foam have on accuracy? I'm sure it has some effect.
