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PICP

This folder contains picp, a PIC16F145x based PIC16F145x programmer.

To program a PIC16F145x with this, all you need is a PIC16F145x programmed with the software in pic/ connected with USB to a computer with the software in pc/. (So you still need to get the first PIC programmed somehow, but after that, you have a very simple and cheap programmer.)

No additional circuit is required, the USB wires are directly connected to the programmer PIC, and the pins of that PIC are directly connected to the PIC that's to be programmed. The reset, data and clock pins are set to high impedance while not programming, so the programmer can be left connected while running your application.

The picp PC software works on both Linux and Windows (and probably on any POSIX system).

Usage

Program a PIC16F145x with the software in pic/.
Compile the software in pc/ and (optionally) put the resulting picp executable somewhere in your PATH. (e.g. /usr/local/bin)
On Linux: Copy udev/40-picp.rules to /etc/udev/rules.d/. On Windows: Connect the programmer and install the 'driver' from inf/ using the device manager.
Connect the ICSP pins (RC0 and RC1) of the programmer and the to-be-programmed chip, and connect RC2 of the programmer to the reset pin (RA3) of the to-be-programmed chip.
Connect the programmer with USB, and use picp program < file to flash a program.

Compiled binaries of both the PIC and the PC software can be found on Github: https://github.com/m-ou-se/picp/releases

Protocol

The programmer is a USB ACM device, which basically means it acts like a simplified serial port. (Linux will recognize it and make a /dev/ttyACMx for it, which is symlinked from /dev/picp0 if you use the provided udev rule. Windows will make a virtual serial port COMx, if you use the provided inf file.)

The protocol that's used to talk with the programmer is very simple. Commands are just single bytes (ASCII characters), and parameters (which are always 14-bit) are encoded as two bytes with the most significant bit set to 1, to prevent any confusion with command bytes.

The commands are:

Command	Description	Reply
`'V'`	Get the programmer version	A newline (`\n`) terminated version string (in ASCII).
`'T'`	No operation (for testing)	One byte: `'Y'`
`'B'`	Begin program mode: Pull the reset pin low, and clock in the magic number 0x4D434850 to get the chip in low voltage programming mode.
`'E'`	End program mode: Set the reset, data and clock pins back to high impedance mode.

Furthermore, the following commmands map directly to the commands specified in the PIC16(L)F145X Programming Specification:

Command	Parameter	Reply	ICSP Command
`'C'`	Data		Load Configuration
`'L'`	Data		Load Data For Program Memory
`'R'`		Data	Read Data From Program Memory
`'I'`			Increment Address
`'A'`			Reset Address
`'P'`			Begin Internally Timed Programming
`'Q'`			Begin Externally Timed Programming
`'S'`			End Externally Timed Programming
`'X'`			Bulk Erase Program Memory
`'Y'`			Row Erase Program Memory

Parameters and replies are 14 bits, encoded as two bytes with the most significant bit set: The least significant 7 of the first byte contain the most significant 7 bits of the data, the least significant 7 bits of the second byte contain the least significant 7 bits of the data.

USB Vendor and Product ID

The USB ID for picp is 1d50:6088. This ID comes from OpenMoko Inc., who are so kind to give away their product IDs to open source projects like this.

Schematic

This is how you should connect the programmer and the target, for the 14-pin packages:

      .-------------.
      |    +------+  '-------[5V]---
      +----|1   14|-----+----[GND]--    USB
      |   -|2   13|-----|----[D+]---  (to PC)
      |   -|3   12|-----|----[D-]---
      |   -|4   11|-    |
      |   -|5   10|-----|--.
      |   -|6    9|-----|-----.
      |   -|7    8|-.   |  |  |
      |    +------+ |   |  |  |
      |   Programmer|   |  |  |
      |             |   |  |  |
 .----|-------------'   |  |  |
 |    |                 |  |  |
 |    |    +------+     |  |  |
 |    '----|1   14|-----'  |  |
 |        -|2   13|-       |  |
 |        -|3   12|-       |  |
 '-[Reset]-|4   11|-       |  |
          -|5   10|-[Data]-'  |
          -|6    9|-[Clock]---'
          -|7    8|-
           +------+
            Target

Copyright

PICP - A PIC16F145x based PIC16F145x programmer.
Copyright (C) 2013 Mara Bos

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program.  If not, see <http://www.gnu.org/licenses/>.

Contact

If you have any questions, feel free to contact me: https://m-ou.se/contact