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CHESTER-X0

This article describes the CHESTER-X0 four-channel I/O extension module. Two variants are available:

  • CHESTER-X0A including 5.0V boost converter

  • CHESTER-X0B without 5.0V boost converter

Module Overview​

Each channel can be used for these applications:

  • Digital input and output
  • Analog input and output
  • Voltage input 0–26 V*
  • Current loop 4–20 mA
  • Dry contact input
  • NPN and PNP input
  • Power output
    • X0A with boost converter: 5 V
    • X0B w/o boost converter: standard 3.0 V (VDD solder bridge) or on request V+ battery rail (V+ solder bridge)

* The CHESTER-M mainboard has TVS protection on the Ax and Bx terminal block pins that starts to protect GPIO above 28 V. Theoretically, you can measure voltages higher than 26 V, but the protection distorts the measurements, or you need to request the board without these TVS diodes or remove them.

Electrical Specification​

  • Continuous output current: 50 mA
  • Peak output current limit: 150 mA

Channel Schematic Diagram​

Depending on the application these configuration options are available for each channel:

  • Enable pull-up resistor 330 kΩ (PUX)
  • Enable pull-down resistor 249 Ω (PDX)
  • Enable voltage divider (gain 1/11) (100 kΩ, 10 kΩ) (CLX)
  • Enable 5V boost converter (CHESTER-X0A only) (ONX)

This picture shows the electric circuit of each channel:

Single-channel circuit: CHX input with varistor, PUX pull-up, PDX pull-down, CLX divider, and ONX 5V switch to GPX/AX

Configuration Table​

The configuration depends on the application.

Signals PUx, CLx, PDx, ONx refer to the schematic above. Green tick ✅ means that the I2C GPIO expander or X0 sends a logic high signal to this configuration signal. However, this is just to understand the modes. You only need to know which mode is set in the ctr_x0_set_mode table column.

ApplicationPUxCLxPDxONxSDK ctr_x0_set_mode
Analog input 0-26 V✅CTR_X0_MODE_AI_INPUT
Dry contact✅CTR_X0_MODE_DEFAULT
NPN input✅CTR_X0_MODE_NPN_INPUT
PNP input✅CTR_X0_MODE_PNP_INPUT
Current loop 4-20 mA✅✅CTR_X0_MODE_CL_INPUT
Power source✅CTR_X0_MODE_PWR_SOURCE
Analog output 0-VDDCTR_X0_MODE_DEFAULT
Digital inputCTR_X0_MODE_DEFAULT
Digital outputCTR_X0_MODE_DEFAULT

CHESTER Pin Configuration Diagram​

CHESTER-X0 terminal block pinout, pins 1-8: VDD, CH1, GND, CH2, CH3, GND, CH4, +V

Pin Configuration and Functions​

PositionSignal NameSignal Description
1VDDSystem VDD rail 3.0 V
2CH1Channel 1
3GNDSystem ground signal
4CH2Channel 2
5CH3Channel 3
6GNDSystem ground signal
7CH4Channel 4
8+VSystem positive rail (*)

*Note: The system positive rail voltage depends on CHESTER power supply option.

Schematic diagram​

A schematic diagram is useful if you program low-level hardware-related code or if you're just curious about how the system is designed.

CHESTER-X0 schematic sheet 1: PCAL6416A GPIO expander and TPS61099 boost converter with module pin headers CHESTER-X0 schematic sheet 2: configuration switch circuits for channels 1 and 2 CHESTER-X0 schematic sheet 3: configuration switch circuits for channels 3 and 4

Module Drawing​

CHESTER-X0 board outline with edge signals: +V, GP0-GP3, SDA, SCL, VDD, GND on top; +V, CH1-CH4, GND, VDD on bottom

CHESTER SDK​

References​