Tymkrs Shift Me (Chainable Shift Register Header Kit)
The Tymkrs Shift Me (v2) kit is a breadboard-friendly shift register module that is capable of being hooked up ad infinitum to another Shift Me. Each board has 8 LED indicator lights and 8 switches that allow you (and your microcontroller or computer) to read or write any of the LEDs/switches through only eight wires. And since they can be connected to each other, if you connect two boards together, you can clock 16 bits in instead of just 8, and so on.
Shift registers? What do they do? How do you make them work?
First read: http://bildr.org/2011/02/74hc595/
Let's first talk about the 74LC595 Shift Register. This is a serial in, parallel out IC that can take 8 bits one at a time, and then show/output them all at the same time. The below are the steps your code would take to make them work.
Vcc: Up to 6V (needs to be the same voltage as your microcontroller) – Usually 3.3 / 5v
QA to QH: Shift Register Outputs.
SER: (Serial) Input for the next pin that gets shifted in.
SRCLK: (Serial Clock) When this pin is pulled high, it will shift the register.
RCLK: (Register Clock) Needs to be pulled high to set the output to the new shift register values, This must be pulled high directly after SRCLK has gone LOW again.
Step 1: Send in a 1 or 0 on the Serial pin. Send the Serial Clock pin a 1. That makes the 1/0 you sent get stored on the first pin. Send the Serial clock pin a 0. Register Clock stays low
Step 2: Send in a 1 or 0 on the Serial pin. Send the Serial Clock pin a 1. That makes the 1/0 you sent get stored on the first pin. What you stored on the first pin before moves automatically to the second pin. Send the Serial Clock pin a 0. Register Clock stays low.
Steps 3-8: Repeat until all 8 pins are filled.....
Step 9. Send the Register Clock (known as a latch) a 1. All eight pins output their information (light up 8 LEDs at the same time)! Note that while the Register clock is low, the outputs will not show their information.
Now let's talk about the 24LC165. This is a parallel in, serial out shift register.
PL: (Parallel Load/Latch) Needs to be pulled high to store the register values in the shift register.
CP: (Clock Input) Toggling this HIGH will send out a single bit.
Q7: (Serial Output) This pin is what you monitor for your serial data.
D0-D7: (Parallel Data Inputs) - This is where you send your parallel data to be transformed into serial data.
Step 1: Set your 8 toggle switches as 1 or 0. Send a 1 to the Parallel Load pin (otherwise known as a latch). All eight bits are stored into the storage register.
Step 2: Send a 1 to the CP (clock input) pin to get the first bit out. Send a 0 to the CP, then send a 1 to the CP. The second bit will come out. As you toggle the CP on and off, the subsequent bits will come out serially on Q7.
So I have this kit, what do I need to know?
There will be TWO options. Please carefully look before purchasing - 1 is for momentary switches, and 1 is for toggle switches!
The 595 is reading serial information from another board or your microcontroller and displaying the parallel information on the eight LEDs.
Pins used: LED Serial, LED Clock, LED Latch
The microcontroller is monitoring the serial information it's receiving from the 165 at all times, and acts upon any changes you may induce via the toggle/momentary switches.
Pins used: Switch Latch, Switch Clock, Switch Serial
There are two options: Momentary Switches or Toggle Switches. The board footprint is able to handle both, though not simultaneously.
These can be daisy-chained one right after another.
We have tested this successfully with 3.3v.
Remember to match the divots on the chip with the divots on the board's silkscreen!
Video showing what it can do: http://www.youtube.com/watch?v=jlt8fjSZiJw
Demo Code: http://tymkrs.com/code/ShiftMe_BitBang_Demo.spin
To return to the Tymkrs Tindie site: https://www.tindie.com/stores/tymkrs/
To return to the Tymkrs Kits site: http://tymkrs.com/kits
