https://github.com/charkster/tang_nano-uart_block_ram

UART interface to a block ram in the Tang Nano FPGA. No pin connections needed, just use the USB UART.
https://github.com/charkster/tang_nano-uart_block_ram

block-ram fpga tang-nano uart

Last synced: about 2 months ago
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UART interface to a block ram in the Tang Nano FPGA. No pin connections needed, just use the USB UART.

• Host: GitHub
• URL: https://github.com/charkster/tang_nano-uart_block_ram
• Owner: charkster
• License: mit
• Created: 2022-10-14T04:12:08.000Z (over 2 years ago)
• Default Branch: main
• Last Pushed: 2022-10-23T00:28:32.000Z (over 2 years ago)
• Last Synced: 2025-01-13T19:26:55.063Z (4 months ago)
• Topics: block-ram, fpga, tang-nano, uart
• Language: SystemVerilog
• Homepage:
• Size: 2.46 MB
• Stars: 2
• Watchers: 1
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
# tang_nano-uart_block_ram

UART interface to a block ram in the Tang Nano FPGA. **No pin connections needed, just use the on-board USB UART.**

Tang Nano supports up to 4k bytes of block ram (I used it all for this example). I use my own **SCARF** protocol where the first transmitted byte is the RNW bit as the MSBit, and the lower 7 bits are the slave ID (127 possible slaves in the FPGA). The next two bytes are the address (MSByte first). If a read is being done the last byte specifies the number of bytes to be read. If a write is being done the write data immediately follows the address.

**Dependancies:**

pip3 install pyftdi

pip3 install pyserial==3.4

Timing Diagram:

![picture](https://github.com/charkster/tang_nano-uart_block_ram/blob/main/images/uart_header1.png)

This example project shows how to implement a block ram, and interface to it using the **USB serial port**. This structure could be used to store data to transmit using a different protocol implemented in the FPGA (like SPMI or USB-PD). If a flip-flop based register map is used instead of the block ram, actions can be triggered by writing to specific bits.

I program my Tang Nano using https://github.com/trabucayre/openFPGALoader

**openFPGALoader -b tangnano uart_blockram_1k.fs**

![picture](https://github.com/charkster/tang_nano-uart_block_ram/blob/main/images/tang_nano_pinout_v1.0.0_w5676_h4000_large.png)