Dual PIC Programmer:

Production (3 Level) Programming

You can buy the boards modified already and tested

-lax Option
Setting the Voltages
Production In-circuit Programming
Making ATE with I2C
Drawings

Microchips production programming algorithm consists of programming at the normal VDD then verifying at VDD-Hi and VDD-Lo.

These 3 levels are set with 3 resistors on the PCB, in a normal LM317 voltage regulator arrangement. When we ship the programmer the voltages are

VDD LO = 4V
VDD MID = 5V
VDD HI = 6V see notes below

Note that earlier devices specified VERIFY at VDDMAX, which was 6V. Recent PIC's have VCC_MAX=5.5V, and you need to change VDD_HI. Note that later flash PIC's don't specify 3 level verify, so you can just use the -lax option

LAX Option

Production programming uses a full verify of the whole memory space at 2 different voltages. This slows it down, and is unneccessary for development.

The -lax option (PP06 -lax .....) means that the programmer programs and verifies at Vdd Mid, and only verifies the part of the program memory that is in the input file.

Changing the Voltages

First download and print the circuit and overlay PDF's

(PDF 71k) (PDF37k)

The diagnostic mode steps through the 3 voltages, so you can use this to check what the actual VDD and VPP voltages are.

PP06 -debug

VDD Hi is set by R4 alone. (This arrangement ensures that software can only make VDD lower)

VDD Mid is set by R2//R4 and T1

VDD Lo is set by R3//R4 and T2

To reduce VDD Lo try resistors around these calculated values.

VddLo	R3
3	365
2.5	244
2	108

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In Circuit Production Programming

When using production programming in-circuit, you need to change the VCC of the whole circuit. You may need to change delays in the program to allow sufficient time for voltages to transition from one level to another.

Here are some ways of using the PICPN to change the whole circuits voltages:

For low power circuits, just connect VDD of the programmer to the DUT and let the PICPN power VDD directly. You will need to watch the delays if the board adds lots of C
use an external LM317T instead of the on board one. Watch the power switch (T9) current rating though.
Use the collectors of T1,T2 to adjust the voltage regulator in your circuit

If this forms part of an ATE system, you might find it useful to use an I2C adaptor to put together other testing components.

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