Real Time Clock (dev. #02)

Real Time Clock (dev. #02)

Current date/time clock. Compatible with esxDOS and mass storage modules: devSD, devMMC, devIDE modules, Just NANO SD. Allows you to program and read time using BASIC. The card comes with a driver for esxDOS: RTC.SYS – allowing to save the correct time when writing files to disk.

The specialized DS1307 clock chip is responsible for measuring time. It stores the current time (year, month, day, hour, minute and second) and updates it every 1 second. Quartz 32768 Hz is responsible for precise
timekeeping. The DS1307, during normal operation, is powered from the ZX Spectrum computer, but after turning off the power – it switches to the CR2032 battery power supply and goes into sleep mode, in which it only
measures time by consuming small amounts of current (approx. 300 nA).

The Atmega32 microcontroller (MCU), clocked at 8 MHz quartz, is used for communication between the 19-wire MUMIO communication bus and the 2-wire I2C bus of the DS1307. Its task is also to simplify the communication protocol of the DS1307 chip into an easy-to-use ZX BASIC language IN and OUT commands.