6.18 EEPROM
1. The Genius uses a 93CS46 EEPROM, which contains special internal data protection logic to minimize the
possibility of data loss.
2. The Genius calibration table is contained in EEPROM memory (U2).
3. US is powered directly by one of the "high current" I/O pins on the CPU and is normally off.
4. When the CPU desires to read or write the EEPROM, it raises the I/O, supplying current to the EEPROM,
then lowers it when the task is complete.
6.19 Analog to Digital Interface
1. U3, an "analog processor" is used to provide the analog to digital interface between the various sensors and
the CPU.
2. The analog processor is being operated at a 14-bit (plus sign) resolution and samples at anywhere between
30 to 50 conversions per second (depending on amplitude of input).
6.20 Theory of Operation: FILAC
MCU Introduction
The heart of the F-2000 thermometer is a Motorola 8-bit microcontroller unit (MCU). This HCMOS single-chip
MCU contains a CPU, clock oscillator, 7744 bytes of PROM, 176 bytes of RAM, 24 bidirectional I/O lines, a
16-bit timer, serial communications interface (SCI), and a serial peripheral interface (SPI).
A 2 mhz crystal oscillator connected between pins 42 and 43 provides the required clock frequency for the MCU.
6.21 Power On Reset
The MC34064P-5 Under Voltage Sensing Circuit (Q11) provides a reliable reset signal for the MCU by holding
the reset line low until the power supply reaches 4.61 vdc. The time delay capacitor, C7, provides an additional
150 ms (approximately) delay to insure that the power supply is fully stabilized before the MCU comes out of
reset. Q11 also causes the reset line to switch cleanly to ground when the power supply voltage drops to 4.59 vdc.
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