PCF8583 Real Time Seven Segment Clock Circuit - 16F88 ~ Scorpionz - Electronic Circuits and Microcontroller Projects

Basic Connection of PCF8583

The PCF8583 is a clock and calendar chip based on a 2048 bit static CMOS RAM organized as 256words by 8 bits. Addresses and data are transferred serially via the two-line bidirectional I2C-bus.

The built-in word address register is incremented automatically after each written or read data byte. Address pin A0 is used for programming the hardware address, allowing the connection of two devices to the bus without additional hardware.

The built-in 32.768 kHz oscillator circuit and the first 8 bytes of the RAM are used for the clock, calendar, and counter functions. The next 8 bytes can be programmed as alarm registers or used as free RAM space. The remaining 240 bytes are free RAM locations.

Block diagram of PCF8583

Features:

I2C-bus interface operating supply voltage: 2.5 V to 6 V
Clock operating supply voltage 1.0 V to 6.0 V at 0 °C to +70 °C
240 × 8-bit low-voltage RAM
Data retention voltage: 1.0 V to 6.0 V
Operating current (at fSCL = 0 Hz): max 50 μA
Clock function with four year calendar
Universal timer with alarm and overflow indication
24 hour or 12 hour format
32.768 kHz or 50 Hz time base
Serial input and output bus (I2C-bus)
Automatic word address incrementing
Programmable alarm, timer, and interrupt function
Slave addresses: A1h or A3h for reading, A0h or A2h for writing

Circuit Diagram

This clock circuit is same as DS1307 - Real Time Clock. The only different is here I used PCF8583 RTC clock ic and change firmware. Because registers of DS1307 and PCF8583 are different.

To save micro-controller pins there are four input keys which are all connected to a single analogue input pin. This pin also drives one of the seven segment display LEDs so it has to be switched between input (to read the analogue voltage) and output (to drive the led). Each key pulls the analogue input to a different voltage level which you can easily read using the ADC (RA0).

Set Time:

Mode : Pressing mode button cycles the display showing 3 different data.

Mode 1 : Time only
Mode 2 : Seconds only
Mode 3 : Stand-by

Set : To change the value, set button must be pressed.

Set 1 : Edit mode, show Minute
Set 2 : Edit mode, show Hour
Set 3 : Return to clock mode

Up and Down : After Pressing set button, you can change the values indicated on clock by using this buttons.

UP : Values ++
In clock mode it will also change the 12/24Hr format.

Down : Values --
In clock mode it will do nothing.

Quartz Frequency Adjustment:

By evaluating the average capacitance necessary for the application layout, a fixed capacitor can be used. The frequency is measured using the 1Hz signal available after power-on at the interrupt output (pin 7). The frequency tolerance depends on the quartz crystal tolerance, the capacitor tolerance and the device-to-device tolerance. Average deviations of 5 minutes per year are possible. See data sheet for more detail.

Use mikroC for compile.

PCF8583 Datasheet

PIC16F88 Datasheet