This is a Tibbit module — part of the Tibbo Project System that allows you to build your own custom embedded device with only the components you need. Start with a Tibbo Project PCB, add Tibbits like this one, then place the built design into a Tibbo Project Box to complete your product.
Tibbit #42: Real-time clock and non-volatile memory with backup battery and interrupt output.
This Tibbit has a DS3234 real-time clock IC from Maxim. It is a temperature-compensated high-accuracy RTC with non-volatile memory. Refer to the Maxim DS3234 Page for a datasheet and other documentation related to the operation of this IC.
The DS3234 RTC has a INT/SQW pin that can be set to trigger at a predefined date/time or to output a square wave signal. The INT/SQW is available to the outside world through the line IO1. That line also is accessible from the CPU, and is multiplexed with the DOUT signal of the DS3234. The multiplexer is controlled by the CS state. When CS is Low, indicating that a SPI transaction is in progress, the multiplexer selects the DOUT line. When CS is High, the multiplexer selects the INT/SQW signal. Therefore, it is only possible to gauge the INT/SQW state when the SPI bus is idle.
This Tibbit carries a backup battery which powers the RTC when the main +5V supply is off.
There are three red LEDs and one green LED. The red LEDs are connected to CS, SCLK and MOSI lines. The green LED is connected to the INT/MISO line.
- Form: M1S
- Power: 5V; consumes 10mA
- Mates with: #19, #20, #21 (limited use), #37
Sample Project The use of this and other I2C/SPI Tibbits is illustrated by a group of Tibbo BASIC test projects.
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 perfect storage for such parameters.
M1S Tibbit Modules Overview M1S Tibbits are single-width modules occupying one standard M socket on a Tibbo Project PCB (i.e. TPP2 or TPP3). Their footprint is roughly 7 × 14 "squares" (one "square" is 2.54 × 2.54 mm). The M1S modules are 12.5mm high.
M1 modules have two rows of 6 pins:
Pins 8-11 are control lines A-D. They provide the interface to programmable modules or other microcontrollers. On Tibbo Project PCBs, these pins are connected to the main processor.
Pins 2-5 are I/O lines facing the outside world. On Tibbo Project PCBs, they go to C Tibbits.
Pins 6 and 12 are the GROUND and +5V power pins. Most Tibbit Modules consume (take) 5V power. There are also power supply Tibbits that generate 5V power from a variety of sources. Those output 5V through pin 12.
Pins 1 and 7 are for the additional +15V and -15V voltages. These are optional and only needed by few Tibbits. A special power supply Tibbit (#12) generates ±15V from the main 5V power.