PIC18F87J94-I/PT

The PIC18F87J94-I/PT from Microchip is a highly integrated 8-bit microcontroller from the PIC18F97J94 family, uniquely combining USB 2.0 Full-Speed connectivity and a segmented LCD controller (up to 368 segments) in a single device. This combination makes it ideal for handheld instruments, medical devices, and data loggers that require both USB communication and LCD display capability. The 128KB Flash and 3,862 bytes of RAM provide sufficient memory for complex application code, USB protocol stacks, and LCD display data. The LCD controller supports up to 46 segment outputs and 8 common backplanes (368 pixels maximum), with an internal charge pump that generates the LCD bias voltages from the single 2.0-3.6V supply, eliminating external bias components. The LCD controller continues to operate in Sleep mode, allowing the display to remain active while the CPU consumes only 60nA in deep sleep. The USB 2.0 Full-Speed device controller with integrated transceiver supports 16 bidirectional endpoints, enabling complex USB device implementations including composite devices. The CTMU (Charge Time Measurement Unit) provides capacitive touch sensing capability without external components, supporting touch buttons, sliders, and wheels on the same pins used for other functions. The hardware RTCC (Real-Time Clock/Calendar) with VBAT backup maintains accurate timekeeping from a coin cell battery when the main power is removed. The 12-bit ADC with 24 channels and the 4 UARTs provide extensive analog measurement and communication capabilities.

The PIC18F87J94-I/PT operates as an 8-bit PIC18 microcontroller with integrated LCD and USB peripherals. Key subsystems include: (1) PIC18 Core – a Harvard-architecture 8-bit CPU with 16-bit instruction word and 8-bit data bus; the pipelined architecture executes most instructions in 2 clock cycles at up to 64MHz (16 MIPS); the linear program memory addressing simplifies C compiler code generation; (2) LCD Controller – generates the AC multiplexed waveforms for driving segment-type LCD displays; the segment and common drivers directly connect to the LCD glass; the internal charge pump generates bias voltages (V1-V5) from VDD; the LCD frame frequency is programmable (typically 30-120Hz); the LCD data is stored in dedicated LCD RAM registers; in Sleep mode, the LCD controller runs from the internal RC oscillator; (3) USB Controller – a full-speed (12Mbps) USB 2.0 device controller with integrated transceiver; supports 16 bidirectional endpoints with ping-pong buffering; a dedicated USB RAM buffer (1KB) stores endpoint data; the SIE (Serial Interface Engine) handles packet formatting, CRC generation/checking, and NRZI encoding/decoding; (4) nanoWatt XLP – multiple low-power modes: Idle (CPU halted, peripherals running), Sleep (all clocks stopped, LCD/RTCC can continue), Deep Sleep (minimal leakage, 60nA); the VBAT mode powers only the RTCC and LCD from a backup battery; (5) CTMU – a precision current source and timer that measures capacitance by charging the unknown capacitance with a constant current for a fixed time and measuring the resulting voltage; touch sensing detects the additional capacitance of a finger on a sensor pad.

• Blood glucose meter: 368-seg LCD shows readings, USB downloads data to PC, RTCC timestamps measurements, CTMU for nav buttons
• Handheld multimeter: LCD displays measurements, 12-bit ADC reads voltage/current, USB for data logging, deep sleep extends battery life
• Industrial data logger: LCD shows real-time values, USB for configuration and data export, RTCC with VBAT for timestamps during power loss
• Thermostat: LCD shows temperature setpoint and schedule, CTMU touch buttons, RTCC for time-based scheduling, Sleep mode with LCD active