591 IEEEcoffee_chip
591 : IEEEcoffee_chip
- Author: Juan Pablo Tabares Cardona
- Description: El Coffee Chip es un sistema de clasificación de granos de café implementado directamente en silicio (ASIC) mediante el proceso de fabricación TinyTapeout (Sky130). El diseño utiliza lógica digital de alta velocidad para procesar señales de frecuencia provenientes de un sensor de color (como el TCS3200), permitiendo categorizar granos en tres estados: Inmaduro, Óptimo y Pasado.
- GitHub repository
- Open in 3D viewer
- Clock: 50000000 Hz
How it works
The Coffee Chip is a hardware-based color classifier designed to automate the quality control of coffee beans. Unlike software-based solutions, this project uses a high-speed digital state machine implemented in an ASIC to process signals directly from a color sensor.
Core Architecture:
- Frequency-to-Digital Conversion: The chip receives a square wave from a TCS3200 sensor through the
ui[0]pin. An internal 26-bit counter measures the number of pulses received within a specific time window (controlled by the system clock). - Finite State Machine (FSM): The controller cycles through different color filters (Red and Green) by driving the sensor's
S2andS3pins (uo[2]anduo[3]). - Classification Logic: Once the color values are captured, the chip compares the frequencies against pre-defined thresholds:
- Unripe: High green component detected.
- Optimal: High red component with low green interference.
- Overripe: Low overall reflection (low frequency in both channels).
- Dual Configuration Mode:
- Static: Uses physical pins (
ui[2]andui[3]) for quick calibration. - Dynamic: An integrated UART Receiver allows the user to update the
R_minandR_maxthresholds on-the-fly via theui[1]pin, enabling fine-tuning for different coffee varieties without changing the hardware.
- Static: Uses physical pins (
How to test
To validate the Coffee Chip, follow these steps:
- Initial Setup:
- Apply a stable 50MHz clock to the
clkpin. - Set
rst_nto low for at least 10 clock cycles, then pull it high to start the system. - Ensure
ena(Enable) is high.
- Apply a stable 50MHz clock to the
- Sensor Connection:
- Connect the OUT pin of a TCS3200 color sensor to
ui[0]. - Connect
uo[0]throughuo[3]to the sensor's S0, S1, S2, and S3 control pins.
- Connect the OUT pin of a TCS3200 color sensor to
- Observation:
- Place a coffee bean in front of the sensor.
- Check the output pins
uo[4](Green LED),uo[5](Yellow/Red LED), oruo[6](Red/Dark LED) to see the classification result. - Pin
uo[7]will pulse high every time a full measurement cycle is completed.
- UART Calibration (Optional):
- Set
ui[4](cfg_sel) to high. - Send a 16-bit value via UART (9600 baud) to the
ui[1]pin to update the internal classification thresholds.
- Set
External hardware
To fully utilize this project, the following external components are required:
- Color Sensor: TCS3200 (or compatible frequency-output color sensor).
- LED Indicators: 3 LEDs (Green, Yellow, Red) with current-limiting resistors connected to
uo[4],uo[5], anduo[6]. - UART Bridge: (Optional) A USB-to-TTL converter (like FTDI or CP2102) to send calibration data from a PC.
- Pull-up/down Resistors: Depending on your PCB setup for the configuration input pins.
IO
| # | Input | Output | Bidirectional |
|---|---|---|---|
| 0 | sensor_in | sensor_s0 | |
| 1 | uart_rx | sensor_s1 | |
| 2 | s0_config | sensor_s2 | |
| 3 | s1_config | sensor_s3 | |
| 4 | cfg_sel | led_unripe | |
| 5 | led_optimal | ||
| 6 | led_overripe | ||
| 7 | debug_ready |