tillitis-key/hw/application_fpga/core/uart
Daniel Jobson 3d7a97ecbc
fpga: remove the API for configuring the UART core
This removes the possibility to configure the bit rate, data bits and
stop bits at runtime from the API. This reduces the
usage of LCs with ~4%.

It is still possible to configure the core before building.

Update digest of application_fpga.bin.sha256
2024-11-26 15:24:12 +01:00
..
rtl fpga: remove the API for configuring the UART core 2024-11-26 15:24:12 +01:00
tb FPGA: Format verilog code 2024-10-22 12:04:19 +02:00
toolruns Update Verilog version to 2005 for linting 2024-04-24 08:44:08 +02:00
LICENSE Make initial public release 2022-09-19 08:51:11 +02:00
README.md fpga: remove the API for configuring the UART core 2024-11-26 15:24:12 +01:00

uart

A simple universal asynchronous receiver/transmitter (UART) core implemented in Verilog. The core is completed and has been used in several FPGA designs.

Introduction

The UART core is used as main communication channel between the TKey device System on Chip (SoC) and the TKey client. The UART contains a 512 byte receive buffer, allowing the SW running on the SoC to not have to wait for bytes and poll them as soon as they are received. The number of bytes in the FIFO is also exposed to the SW through the ADDR_RX_BYTES address.

The number of data and stop bits can be configured prior to building the core.

The bit rate can also be configured prior to building the core. It should be based on the target clock frequency divided by the bit rate in order to hit the center of the bits. For example, a clock of 18 MHz and a target bit rate of 62500 bps yields: Divisor = 18E6 / 62500 = 288

API

ADDR_RX_STATUS: 0x20
ADDR_RX_DATA:   0x21
ADDR_RX_BYTES:  0x22

ADDR_TX_STATUS: 0x40
ADDR_TX_DATA:   0x41

Implementation notes.

The FIFO allocates a single block RAM (EBR).