Tiny Tapeout > Tiny Tapeout Chips > Tiny Tapeout SKY 26b > 686 UART - Controlled Frecuency Meter & Timer - IEEE
686 UART - Controlled Frecuency Meter & Timer - IEEE
686 : UART - Controlled Frecuency Meter & Timer - IEEE
- Author: Richard Alfredo Tarqui Mamani & Gustavo Ismael Chavez Mamani
- Description: Frequency meter, pulse counter, and programmable timer controlled via UART at 115200 baud.
- GitHub repository
- Open in 3D viewer
- Clock: 50000000 Hz
UART-Controlled Frequency Meter & Timer
How it works
This project integrates three high-precision measurement tools into a single 1x1 ASIC tile, specifically optimized for the Sky130 process:
- Programmable Timer: A countdown timer set via UART in
HH:MM:SSformat. It uses a cascaded counter architecture to minimize area usage. - Frequency Meter: Measures the frequency of an external signal on
ui_in[1]using a precise 1-second gate window. - Pulse Counter: Records the total number of falling edges detected during the measurement period.
The entire system is managed via a UART interface operating at 115200 baud (8N1).
Inputs/Outputs Detail
| Pin | Label | Direction | Description |
|---|---|---|---|
| ui[0] | RX | Input | UART Data Input. Receives ASCII commands. |
| ui[1] | Signal | Input | The external signal to be measured (Frequency/Pulses). |
| uo[0] | TX | Output | UART Data Output. Transmits telemetry frames. |
| uo[1] | Frame OK | Output | Generates a 1-clock cycle pulse when a full telemetry frame is sent. |
| uo[2] | Active | Output | HIGH when the timer is running and measurement gates are open. |
UART Command Set
Hhh:mm:ss: Load timer value (e.g.,H00:05:00for 5 minutes).I: Initialize (Starts the countdown and measurement).R: Reset (Stops the system and clears all registers).E: Enable telemetry (Starts periodic data reporting).Y: Stop telemetry (Disables data reporting).
Telemetry Data Format
When enabled, the chip transmits a 13-byte frame at 115200 baud:
$ [Count_H] [Count_L] / [Freq_H] [Freq_L] / [Status] / [#] / [\n] [\r]
- Status Byte: - Bit 2: System Active.
- Bit 1: Timer Finished.
- Bit 0: UART Command Error.
How to test
- Connect a USB-to-UART bridge to
ui_in[0]anduo_out[0]. - Connect a signal generator or a pulse source to
ui_in[1]. - Use a serial terminal at 115200 baud.
- Send
H00:00:10to set a 10-second window. - Send
EthenI. You will see data frames appearing in your terminal.
IO
| # | Input | Output | Bidirectional |
|---|---|---|---|
| 0 | UART RX (ASCII Commands) | UART TX (Telemetry Frame) | unused |
| 1 | External Signal Input | Frame OK (Pulse on completion) | unused |
| 2 | unused | Active (HIGH during measurement) | unused |
| 3 | unused | unused | unused |
| 4 | unused | unused | unused |
| 5 | unused | unused | unused |
| 6 | unused | unused | unused |
| 7 | unused | unused | unused |