348Tibbo Project System (TPS)
© Tibbo Technology Inc.
Details
This Tibbit is based on the DS3234 IC from Maxim Integrated. This is a temperature-
compensated high accuracy RTC with non-volatile memory. Refer to Maxim
Integrated datasheet for operation details.
The DS3234 RTC has the -INT/SQW pin, which can be set to trigger at a predefined
date/time or output a square wave signal. The -INT/SQW is available to the outside
world through the line IO1. -INT/SQW is also accessible from the CPU. The line is
multiplexed with the DOUT signal of the DS3234. The multiplexor is controlled by the
CS state. When CS is LOW, thus indicating that an SPI transaction is in progress,
the multiplexor selects the DOUT line. When CS is HIGH, the multiplexor selects the
-INT/SQW signal. Therefore, it is only possible to gauge the -INT/SQW state when
the SPI bus is idle.
The Tibbit carries a backup battery which powers the RTC when the main +5V
supply is off.
LEDs
There are three red LEDs and one green LED. Red LEDs are connector to CS, SCLK,
and MOSI lines. Green LED is connected to the -INT/MISO line.
Sample project
The use of this Tibbit is illustrated by a Tibbo BASIC test project. Yo can find it
here: https://github.com/tibbotech/CA-Test-Tibbit-42.
The non-volatile memory of the DS3234 can be used from within the STG (settings)
library. Projects often have parameters (settings) that change too often to be
stored in the EEPROM, yet must be preserved even when the power is off. The non-
volatile memory of this Tibbit offers a perfect storage for such parameters.
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