710 SoCET UART with FIFO buffers
710 : SoCET UART with FIFO buffers
- Author: Miguel Isrrael Teran, Yashashwini Singh, Michael Li, Rafael Monteiro Martins Pinheiro, Vito Gamberini
- Description: General-purpose UART with hardware control flow and FIFO buffer capacity developed by Purdue's SoCET team
- GitHub repository
- Clock: 50000000 Hz
How it works
This project is a UART module that includes FIFO buffers to store bytes of data. The module has standard UART input and output pins, such as rx, tx, cts, and rts. Additional inputs allow the configuration of operation mode(s): Idle, RX, TX or Buffer Clear, and desired baud rate is user-configurable through the Control pins. Bidirectional data pins are used to send and receive test data. Additional outputs include an error flag, as well as the TX FIFO's full flag, and the RX FIFO's empty flag.
How to test
Steps for testing are the following:
- Supply a 50 MHz clock signal to the UART
- Configure the control settings:
Control[1:0](ui[3:2]) are used to choose between preloaded baud rates. Here are the following baud rate configurations based on the values ofControl[1:0]:
Value of ui[3:2] |
Baud rate (bits/s) |
|---|---|
| 0 | 9600 |
| 1 | 19200 |
| 2 | 38400 |
| 3 | 115200 |
Control[3:2] (ui[5:4]) set the UART's mode of operation for the current byte of data being processed. Each non-idle control signal must be preceded with an idle signal to perform a valid transaction/manage the FIFO buffers. Here are the following UART mode configurations determined by the values of Control[3:2]:
Value of ui[5:4] |
Mode Configuration |
|---|---|
| 0 | IDLE |
| 1 | TX |
| 2 | RX |
| 3 | BUFFER CLEAR |
- If you have 2 PCBs with the TT09 ASIC, you can load the same UART design in both and cross-connect their
rx,tx,cts, andrtspins as shown in the image below. Then, you can use one of them as a Transmitter and the other as a Receiver. If you only have 1 PCB, you can test the UART with the FT232RL Mini USB to TTL Serial Adapter Module (see next section).
<br> <img src="./uart.png" width=300 alt="UART Connection"> <br>
External hardware
We suggest using switches for the Control pins (this way you can keep the mode of operation stable). Image below shows the FT232RL module that can be used for testing and connecting serially to a computer's USB port. More information on the product can be found here.
<br> <img src="./ft232rl.png" width=300 alt="FT232RL Mini USB to TTL Serial Adapter Module"> <br>
IO
| # | Input | Output | Bidirectional |
|---|---|---|---|
| 0 | rx | tx | data[0] |
| 1 | cts | rts | data[1] |
| 2 | Control[0] | err | data[2] |
| 3 | Control[1] | tx_buffer_full | data[3] |
| 4 | Control[2] | rx_buffer_empty | data[4] |
| 5 | Control[3] | data[5] | |
| 6 | data[6] | ||
| 7 | data[7] |