SSR-25VA

AN1355 A Complete Electronic Watch Based on MCP79410 I2C™ RTCC Author: Alexandru Valeanu Microchip Technology Inc. On-chip Digital Trimming/Calibration of the Oscillator Operates down to 1.3V VBAT Minimum Operating Temperature Range: - Industrial (I): -40C to +85C Multi-function Pin: - Open-drain configuration - Programmable clock frequency out - Programmable alarm output Interrupt Capability (based on the 2 sets of Alarm Registers, ALM0 and ALM1) Time-stamp Registers for holding the Time/Date of Crossing: - from VDD to VBAT - from VBAT to VDD INTRODUCTION An increasing number of applications that involve time measurement are requiring a Real-Time Clock/ Calendar (RTCC) device. The MCP79410 is a feature-rich RTCC that incorporates EEPROM, SRAM, unique ID and time-stamp. FEATURES OF THE RTCC STRUCTURE I2C™ Bus Interface RTCC with Time/Date Registers: Year, Month, Date, Day of Week, Hours, Minutes, Seconds Support for Leap Year Low-power CMOS Technology Input for External Battery Backup (maintains SRAM, RTCC and Timekeeping) On-board 32,768 kHz Crystal Oscillator for the RTCC SCHEMATIC The schematic includes a PIC18 Explorer demo board and the I2C RTCC PICtail™ daughter board as shown in Figure 1. FIGURE 1: SCHEMATIC DB7 - 0 LCD LUMEX RS E SCK MCP23S17 SPI Expander CS SDI VDD RC5/SD01 C4 = 0.1 uF RA2 10K S1 RB0 VDD VDD 2K RA4/T0 CKI C3 32.768 kHz 1 X1 10pF Y VDD 8 2K PIC18F87J11 VDD 10K 2 C4 R4 X2 RTCC MCP 79410 MENU KEY MFP 7 S2 ...