We have been using the 3M/Dynapro Analog Resistive Touch Screen
Controller part number 95704 (V1.2), which is a programmed PIC16C5X
microcontroller. The 95704 has become obsolete. The 95704 uses an
external multiplexer and ADC. We are using the UPDD (V3.8) touch
screen driver, which runs in embedded XP and has the following hard
coded settings:
Model 3M SC3 Serial
Baud rate 2400
Parity None
Data bits 8
Stop bit 1
The RS-232 Protocol is a three byte protocol:
Byte B7 B6 B5 B4 B3 B2 B1 B0
1 1 P X9 X8 X7 Y9 Y8 Y7 (P : 0 Pen-up, 1
Pen-down)
2 0 X6 X5 X4 X3 X2 X1 X0
3 0 Y6 Y5 Y4 Y3 Y2 Y1 Y0
While we have been investigating replacement controllers, there is a
business case for trying to see if we can find a form, fit, and
function replacement for the 95704. Specifically, continued support of
systems with the UPDD driver in this configuration and continued
production of the current board.