#00-3, M1S: Two Direct I/O Lines, +5V Power, Ground

A gray M1S Tibbit.

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

Mates with: #19, #20, #21, #28, #29, #30, #35, #36, #38, #39, #41

See also: #00-1, #00-2


As with #00-1 and #00-2, this Tibbit "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 this is often sufficient.

The GND and +5V lines may be necessary when using Tibbit #00-3 with #21 (four terminal blocks). Tibbit #21 doesn't have its own ground or power, so those must come from the neighboring "M" device, such as Tibbit #00-3.

Another use for Tibbit #00-3 is with "C" devices that implement various sensors:

All of the above sensors use the 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 a 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.  

#00-3, M1S: Two Direct I/O Lines, +5V Power, Ground