#00-3, M1S: Two Direct I/O Lines, +5V Power, Ground
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Function: Two directly exposed I/O lines of the microcontroller plus the +5V output and ground lines
Form factor: M1S
Category: Blank module
Special needs: ---
Power requirements: 5V/20mA
As with Tibbits #00-1 and #00-2, this one "gets the CPU lines out". The only difference is that one of the lines is replaced by +5V power, and another line is ground. This leaves you with only two CPU lines, but very often this is sufficient.
The GND and +5V lines may be necessary when using this Tibbit with "C" Tibbit #21 (four terminal blocks). #21s doesn't have its own ground or power, so those must come from the neighboring "M" device, such as this Tibbit.
Another use for this Tibbit is with "C" devices that implement various sensors:
•#28: Ambient light sensor
•#29: Ambient temperature meter
•#30: Ambient humidity meter
•#35: Barometric pressure sensor
•#36: 3-axis accelerometer
All of the above sensors use I2C interface to talk to the main CPU. I2C only requires two CPU lines. The remaining two lines are ground and +5V power.
Note that a CPU I/O line has the voltage swing from 0-3.3V when the line is enabled (io.enabled= 1- YES). The voltage may be close to 5V when the line is disabled (io.enabled= 0- NO). This is because the CPU has weak pull-up resistors connected to 5V.
Two yellow LEDs are connected to two control lines of the CPU (through buffering gates). LEDs light up for the LOW state of control lines.