You can use 1.8 to 5.5V as supply voltage
Speed is up to 64 MHz, but we use 8 or 32 with this crystal. If you want, you can use the internal osc and you get the fill 64 MHz
you can implement a bootloader like on the arduino
8-Channels of 12-Bit A/D
5 Capture/Compare/PWM Pins
2 8-bit-timers, 3 16-bit-timers
2 analog comparatos
1 CAN 2.0B Interface
1 CMTU (to read in a PWM-Signal for example)
So, what you get for the buck... No, it is not a raspberry-pi-zero, and not this powerfull, but
it is available ;)
The controller of the Fab-Pic is a PIC18F26K80. You can use any other 28-Pin-PIC18 if you want, this
was just the type i had laying around here.
HINT: you can get free samples from microchip! Up to 6 ICs (also eeproms and so on) every 4 weeks.
The samples are absolutely free of charge!
Next to the controller is a 8-Mhz Crystal with to 18pF capacitors. The ICSP-Interface is breaked out,
there is a jumper for choosing the power-input (programer or external supply), a LED and a button.
Every Pin that is not needed by the board itself is breaked out to your bread-board. These are 20 Pins!
Some facts to the 26K80:
As you can see, this thing brings power to your breadboard...
To program it, you need a programer. The cheapest i´ve found is the "PicKit 3" from Microchip itself.
You can find it on amazon or every electronic-supply-store for about 30$.
What you get is not just a programer but also a tiny debugger that can handle up to three breakpoints. Very usefull!!!
Let´s explain the circuit:
This is the pinout of the 26k80. There are some pins that are not breaked out, due to the fact that these
are only needed for programing, the oscilator and power-supply. But you get:
From the left-side: Pins 2,3,4,5,6,7,11,12,13 and 14
and from the right-side: Pins 26,25,24,23,22,21,18,17,16 and 15
Pins 8, 19 and 20 are used for the power supply. At the shortöedn of the Fab-Pic you will find two pins,
Ground and Vdd.
Pins 9 and 10 are used by the crystal. As you can see in the datasheets the Pic has a lot of configurations
for the oscilator. Our Crystal has 8-MHz, but you can also use the internal PLL of the pic and get 32MHz
out of it. Or you can use the build-in crystal which runs on 16 MHz, with PLL enabled you get 64 MHz
out of it. So the right speed for every task...
Pins 27 and 28 are used by the ICSP. Surely they can also be used by your circuit, but
to these pins the LED (28) and the button (27) are connected.
HINT: the LED is on RB7, the button on RB6
Some words about the ICSP:
Every Pic uses a method called "High-Voltage-Programing". This means,
that the progamer tells the pic by a 12V-Signal on the MCLR-Pin that it has to go
to a programing-state. The program itself is then send serial (clock and data) to the
Pins 28 and 27.
The problem is, that the MCLR-Pin is also the reset-pin and it has to be on high-level
when the controler shall run.
Because of this the MCLR is connected to VDD by a schotcky-diode and a resistor.
This protects the circuit from the 12V of the programer.
Second problem is the supply-voltage:
The pickit can supply the circuit with up to 400mA out of your USB-port.
But if you connect an external-supply and the pickit at the same time, it COULD
bang your USB-Port. So i´ve placed a jumper next to the ICSP-Interface. With this
you could choose which supply is used.
Here you can also see the connection for the LED and the button.
Be aware, that you don´t push the button while programing!
And this is what the very first Fab-Pic looks like:
I´ve made the board with our LPKF S63, our LPKF Pick-n-place and a reflow-oven.
The process is explained already in week 4.
If you want the eagle-files, here they are:
To test the board i wrote a little program that just toggles the LED on and off by a button press.
In week 8 we will have a assignment in "embedded programing", there i will explain the toolchain
and some basic programs!
After some working with the fab-pic i´ve made some smaller changes:
The 10-Pin-Header on both sides is now a 11-Pin-Header. The two new pins are routed
to GND and +5V (ICSP-Port upside, GND left, +5V right).
The ICSP has now a shotky-diode in the 5V-Line. This way you can power the fab-pic external while the programmer
is connected. With the jumper next to the icsp you can decide if the circuit is powerd by the programmer and your USB-Port
or by an external source. Small circuits can be powered by the USB, but only up to 500mA!
The button on the fab-pic has now an external pull-up. This works much better than the build-in one...
The new Pin-Out:
Here are the eagle files: fab_pic_v2.zip
So long, have fun!