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MCP2030 Bidirectional Communication Demo Kit User’s Guide

3.3 MCP2030 TRANSPONDER DEMO BOARD

3.3.1 Technical Specifications

3.3.2 Microcontroller (PIC16F636)

The Transponder Demo Board uses a PIC16F636 microcontroller. This MCU is the

same device that is used inside the PIC16F639 which is a dual die package device

(PIC16F639 = PIC16F636 die + MCP2030 die in a single 20-pin package). The MCU

interfaces with the MCP2030 stand-alone analog front-end device for LF

communications and the MCP3421 delta-sigma analog-to-digital converter for RSSI

data conversion. When the MCU is first powered-up, it writes the MCP2030

configuration registers and also writes the configuration register of the MCP3421 ADC

(for 16 bit and one-shot mode).The MCP3421 stays in a low power standby mode after

one conversion. The MCU also stays in a low power sleep mode while the MCP2030

is looking for a valid LF command.

The MCU is waken up by the demodulated output from the MCP2030 or by a button

switch event (SW3 and SW4). The MCU decodes the demodulated output data from

the MCP2030. If the data is a valid command, it blinks the green LED (D6) and reads

the RSSI value by controlling the MCP3421 ADC. Once the RSSI value is acquired, the

MCU feeds the transponder ID and the RSSI data into the 433.92 MHz UHF

transmitter. The transmitted data from the UHF transmitter is detected by the RF

receiver in the Base Station Demo Board and the data is displayed on the LCD.

When a button switch is pressed, the MCU feeds a corresponding data into the UHF

transmitter. The red LED (D7) blinks each time the transponder transmits the UHF

response. The red LED also blinks when the transponder receives invalid data.

3.3.3 Three-Input LF (125 kHz) Front-End (MCP2030)

The MCP2030 detects the Base Station Demo Board’s LF command using three LF

antenna coils that are mounted on the Transponder Demo Board PCB. The Configura-

tion registers of the MCP2030 are configured by the MCU when the Transponder Demo

Board is powered up the first time, and are re-configured during operation. The MCU

controls the MCP2030 for two different outputs: (a) Demodulated data and (b)

Received Signal Strength Indicator output (RSSI). When it is detecting input signals,

the device is configured for the demodulated data output. Once the MCU finds a valid

LF command, then the MCU re-configures the MCP2030 for the RSSI output. In this

case, the MCP2030 outputs the RSSI current that is proportional to the LF input signal

LF Input Frequency: 125 kHz

LF Input Modulation Format: Amplitude Modulation

Encoding Method: Pulse Width Modulation (PWM)

Operating Voltage: 2 - 3.6V. See Note 1

LF Input Sensitivity: ~3 mVPP. See Note 2

LF Detection Range: Up to 3 meters

Transmitting Frequency: 433.92 MHz

UHF Range: Up to ~ 20 meters

Bidirectional Communication Range Up to 3 meters

Note 1: The minimum requirement for V

of the MCP3421ADC is 2.7V. For

the V

less than 2.7V, the ADC result of the RSSI value may not be

stable.

2: Contact Microchip Technology Inc. for the device option with higher

than 3 mVpp sensitivity.