AN897 Datasheet, PDF (13/16 Pages) Microchip Technology – Thermistor Temperature Sensing with MCP6SX2 PGAs

AN897
A.2.6
FIRMWARE FOR THE SIGNAL
ANALYSIS PICtail DAUGHTER
BOARD
PICA2Dlab.hex is the standard file that supports the
PICkit™ 1 Signal Analysis PC Program. The PGA and
10-bit ADC configuration are selected in the Signal
Analysis PC Program and written to the PIC16F684.
The PIC16F684 then sends the command(s) over the
SPI bus to the PGA.
Therm_PGA1.hex implements the first design. It
supports the PICkit 1 Signal Analysis PC Program, but
with reduced functionality; its output can be viewed on
the strip chart only. The results need to be manually
converted to temperatures (codes 0 to 1023 convert to
0.0°C to 102.3°C).
Therm_PGA2.hex implements the second design. It
supports the PICkit 1 Signal Analysis PC Program, but
with reduced functionality; its output can be viewed on
the strip chart only. The results need to be manually
converted to temperatures (codes 0 to 1023 convert to
0.0°C to 102.3°C).
A.2.7 INTERFACE DETAILS
A more detailed look at how the Thermistor PGA PICtail
Daughter Board interfaces with the other boards is
shown in Figure A-4.
Thermistor PGA
PICtail™ Daughter Board
Signal Analysis
PICtail™ Daughter Board
Temperature
+5V
Test Point
GND
Test Point
CH0 Input
Test Point
CH1 Input
Test Point
Thermistor
Voltage
Divider
PGA
MCP6S22
+5V
GND
4
SPI Bus
V_OUT
Serial
EEPROM
4
SPI™ Bus
PIC16F684
ADC
+5V
GND
2
FIGURE A-4:
Detailed Interface Diagram.
PICkit™ 1
Flash Starter Kit
PIC16F745
USB
to PC
 2004 Microchip Technology Inc.
DS00897B-page 13