In circuit serial programmer for PIC16F87X

Intro Description Firmware Host software Schematics & PCB Questions? Alternative

Intro

Here you can find all resources you need to build your own in-circuit serial PIC16F87X programmer.
After experimenting with the PIC16F84, time had come to move on to more powerful devices, such as the PIC16F871.
These devices offer a low voltage progamming (LVP) mode. This basically means that it is possible to modify the contents of the program memory without applying a high voltage (12 V) to the device.
Being used to the remove-plug-burn-remove-plug-test programming method of the 16F84, I decided to build my own ICSP (in-circuit serial programmer).

Description

Features:

Interface:

The programmer communicates to a host through a serial port. All commands are character-based. The serial port settings are: 9600 bps, 8 databits, no parity and 1 stop bit (9600, 8N1). When a command is finished, the programmer returns 'OK'.
Overview of the instruction set:

R
Read the contents of the program memory (PM). This command must be followed by the highest address that has to be read.
E.g. R0078 will dump the contents of the address range 0x0000 to 0x0078 of the PM to the serial port.
I
Dump the contents of the configuration memory to the serial port. Configuration memory extends from location 0x2000 up to 0x2007 with the first 4 locations containing the ID locations, location 0x2006 containing the device ID and the last location describing the configuration word.
X
Bulk erase the device.
H
Remove code protection from the device. When the code protection bits are set in the configuration word, all PM locations read as 0x00. All further programming of the device becomes impossible. It is advisable to first send this command to the device you want to program before attempting any other programming.
WARNING: All memory contents will be erased if the device was under code protection.
1 (one)
Put the device in run mode.
0 (zero)
Put the device in reset mode.
P
Enter program mode. This command must be followed by a wait of 100 ms. Then you can choose the following options:
P
Program the PM of the device. This command must be followed by a sleep of 100 ms. Then you can start sending lines of the hex file to the programmer. The leading semicolumn must be removed. If the programmer encounters a CRC error in the received data, it will raise the error flag (corresponding LED on the programmer will light up). After this error, a hard reset has to be performed. If no error is encountered, the programmer will transfer the data to the device under programming and burn it in flash. After successfully completing this task it will return a '1' (one) to the host to designate it is ready to receive the following line of data. This process will stop after an 'end-of-file' line is received ('00000001FF').
C
Program the configuration locations of the device. The configuration locations comprise the ID locations and the configuration word. They are sent in the following format: 0540000000 + ID0 + 00 + ID1 + 00 + ID2 + OO + ID3 + config word + CRC.
The CRC is the value one has to add to the sum of all 8-bits hex values of the line to obtain zero. E.g. the line 0500240528 has CRC AA because 05 + 00 + 24 + 05 + 28 + AA equals 0x100. The leading bits are removed (overflow), so this results in 0x00.

Programmer firmware

Current version of the firmware is 1.04.

You can download the flash-and-burn hex file (4 kB).

The MPLAB project with all source files can be found here.

Host software

Current stable version is 0.2. It completely supports programming PIC16F87X devices. Read and verify operations are not supported by the software yet. The complete host software setup package for the picprogrammer can be downloaded here (zipped, 2,6 MB).
If you only need the executable file, e.g. when you are upgrading from a previous version, pick it here (24 kB, zipped).

David Rojas kindly provided the software with some updates. Latest development release is v0.4. Download the complete VB project source code here (zipped, 72 kB). Changelog

The GUI looks like this

Schematics and PCB

I designed a small PCB for the programmer. The files are made using the freeware version of Eagle from CadSoft. You can get it here.

Some pics of the the proto-board circuits.

Programmer

The IC on the left is a MAX233. It converts the signal levels coming from the host into logic levels understood by the PIC16F84 (located on the right side). On the far right side you see the oscillator for the PIC. In the lower left corner you see the connector to the target system. Next to that, there are some status LEDS.

Target system

The target system consist of a PIC16F871 in a PLCC44 socket (square IC in the middle, kinda' hard to miss this one, isn't it ;-). Together with it's oscillator and some status LEDS it's a basic platform for testing the programmer.

Questions ?

Q: Is it working?
A: I know of one person who rebuilt this project and uses it to program his 16F877.
Q: I get the error message "Programmer not responding" when I try to burn a hex file into a device...
A: First check if the programmer is well connected and powered by opening the log window ("Prefs"-menu and then select "Log window"). Then reset the programmer. The intro message of the programmer showing its version number should apper in the log window.
If this is OK, then make sure that the HEX file is in Intel HEX8 format. If you use MPLAB for your project you can check this by selecting the "Project" menu. Click on "Edit project..." and select the hex file in the "Project files" box. Choose the "Node properties" button and make sure the "INHX8M" setting is selected.
Q: Can I use this programmer if I run a Linux OS?
A: Yes, theoretically you can. However, host software is not available. If I have time, I will rewrite the programmer code in C so it will be more easy to port it to other platforms. But this is not a priority to me. If there are volunteers, just let me know.
Q: Is the programmer free for use?
A: Yep, no matter for what purpose you like to use it. If you however make a giant 'hole in the market' application with it and you earn so much money that you don't know what to do with it, I will of course not refuse the offer from your part to install that heated open air swimming pool in my garden ;-) Oh, and yes, be kind and don't use this programmer do create that neodymium-yttrium-pumped-crispy-double-ribble-mother-in-law-toaster :-)

Alternative

If you are not into building a programmer yourself, I would suggest you to have a look at the WARP-13 programmer. It is a multi-PIC programmer that supports high-voltage programming of most used PIC microcontrollers. I bought such a unit myself and use it for all non-low-voltage programming. As supplier I can recommend Dontronics for both their pricing, the customer support and the speed of delivery. (My programmer arrived within 5 working days!!)


Host software changelog

v04 update by David Rojas

v03 update by David Rojas

In case you have any other questions or comments, feel free to contact me.


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Lieven Hollevoet,