Mini LOGGER V1.0 Block Diagram

Mini LOGGER V1.0 Block Diagram
Mini LOGGER V1.0 Block Diagram

Features of the MiniLOGGER V1.0 are as follows:

# Analog input: 8-channel single-end -99mV to + 999mV
# Analog-to-Digital Converter: integrated type converter, CA3162, with 1mV resolution at 4Hz sampling rate
# Pulse input: 1-channel TTL input
# Memory: battery backup SRAM 628128x2, 256kB (using MAX691 and +3V Lithium battery)
# RTC: battery backup DS1202
# Interval between sample: 10s to 600s
# Serial port: 9,600 baud for uploading the records
# Manual start/stop recording for standalone use
# Automatic start/stop recording with clock setting for daily measurement, say start 06:00 and stop 18:00
# Direct connected to WWW server for remote data retrieving
# ASCII formatted record for easily importing to EXCEL or any Scientific Plot Program

A simplified block diagram of the MiniLOGGER is shown in Figure 1. The CMOS analog multiplexer, 4051 provides the output for 8-channel single-end input to an analog-to-digital converter chip, CA3162. The CA3162 is connected in free running mode. The digital output is 4-bit BCD started with MSD, NSD, and LSD. The pulse period of MSD is 2ms. The 89C2051 runs solar3.hex, the firmware that controls 8-channel reading and receives external pulse. When the chip was triggered by INT0 signal, it will send the digital value in ASCII format through TxD pin;


The format is in short form started with * then analog channel 0, 208mV, channel 1, 190mV and so on. The number 000000 is number of pulse input.

The 89C55 reads such record with time stamped read from DS1202 and saved into SRAM. Now it saves also DATE/TIME and provides comma for each channel separation.


There's also a supervisory and power supply chip, MAX691 for battery backup to SRAM and RTC, MAX232 for RS232 converter, and ICL7660 negative voltage converter.

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