608 Tiny Calculator
608 : Tiny Calculator
- Author: Andy Gong
- Description: A tiny calculator chip with built-in I/O drivers
- GitHub repository
- Open in 3D viewer
- Clock: 0 Hz
How it works
This project is to function as a tiny 16-bit calculator that can directly read keypad inputs from an external connected 4x4 keypad (for 0x0 to 0xF input) and operation keys (+ - * / = AC (neg)). The output will be decoded to be used with 5 common-cathode 7-seg display, with the support of external shift registers with serial input and shift clock (optionally with a storage register and output enable active low pin).
How to test
Connect the keypad IO pins to a physical keypad with key presses being shorts between row and col pins, and wire the operation keys as active-high buttons with pull-down resistors. Connect the output pins to a shift register which the output pins are connected to the anodes of a common-cathode 7-seg display.
Alternatively, the pins can all be connected to a microcontroller that simulates the pins' functionalities.
External hardware
- 4x4 keypad with numbers 0x0 to 0xF, with button presses being shorts between corresponding row and col pins. The keypad should have 8 wires, 4 for columns and 4 for rows.
- Diodes are recommended to prevent shorts when multiple keys are pressed.
- 6 active-high buttons with pull-down resistors for operations:
+,-,*,/,=,AC,(neg). - Shift Registers (optionally with active-low output enable pin, and storage register)
- Common-cathode 7-seg displays.
IO
| # | Input | Output | Bidirectional |
|---|---|---|---|
| 0 | i_BL0 | o_WL0 | o_ADD |
| 1 | i_BL1 | o_WL1 | o_SUB |
| 2 | i_BL2 | o_WL2 | o_MUL |
| 3 | i_BL3 | o_WL3 | o_DIV |
| 4 | i_ADD | o_SER | i_EQ |
| 5 | i_SUB | o_SRCLK | i_AC |
| 6 | i_MUL | o_RCLK | i_NEG |
| 7 | i_DIV | o_OE_n | i_NEG_EN |