R36US0002EU0100 Rev 1.00
Page 13
Aug 26, 2021
RTD120D-EVK Evaluation Kit Software Manual
3. Appendix A: Background Information
The following high-level block diagram introduces the structure of this EVK, followed by a basic functional
description.
With reference to the diagram, gas enters from the openings in the sample chamber and the infrared light
source – in our case a lamp driven by a lamp driver circuit (a linear regulator with soft-start feature) emits infrared
light intermittently to penetrate the gas being measured. The dual-channel thermopile sensor is used to
simultaneously measure the infrared light intensity of both the sensitive wavelength of CO
2
, and of the reference
wavelength. The reference light is not affected by CO
2
.
MCU
RA4W1
3.3V
GPIO
BLE
• Thermopile to PC bridge
• Format conversion
• Basic UI
• System control
• Communications
• Integrated Data Flash
(for calibration parameter, etc.)
HS3001
Temp/Humidity
Sensor
GPIO
pushbutton switches
Linear Regulator
with soft-start
ISL80101
DC/DC (3A)
ISL80101
5V
Character LCD
(16 character x 2 lines)
USB Connector
Lamp
Driver
CO2 Detector Board
Dual Thermopile
RH5Z1222D20GZO#ADO
Digital
Regulator
Lamp
Sample
Chamber
Antenna
Connector
USB
Vcc
CO2
REF
THERMISTOR
MPRLS0025PA
00001A
Barometric
Pressure
Sensor
INT
A/D Converter
A/D
A/D
EOC
A/D
Dual Op-amp
ISL28233FBZ
I2C
Legend
MCU/MPU
Analog/Power
Sensor
