Deprecated! Merged into core
uDMA is an API for interfacing an Arduino Micro with SRAM over an 8-bit parallel bus. This is intended for an 8-bit homebrew computer where the Arduino is paired with an 8-bit CPU such as a Zilog Z80. In this configuration, the Arduino can be used to load code into SRAM, which can subsequently be run on the CPU.
Presently, the pin configuration is hard-coded (for Arduino Micro) and the address bus is limited to 10-bits, but this may be made generic in the future.
This package is intended to be used with PlatformIO, but the source files can be manually copied into a project when using the Arduino IDE.
To add uDMA to an existing PlatformIO project, modify the platformio.ini configuration file as follows:
lib_deps =
https://github.com/trevor-makes/uDMA.git
uDMA is distributed under the MIT license
uDMA should be initialized by calling setup().
The Arduino's connection to the bus can be set to either read, write, or floating by calling enable_dma_read(), enable_dma_write(), disable_dma(). The floating/disabled state should be used when another device (i.e. a CPU) is actively using the bus.
A single byte of data can be read/written using read_byte() and write_byte():
enable_dma_write();
write_byte(address, data);
enable_dma_read();
byte data_in = read_byte(address);
disable_dma();
The read_string() and write_string() functions work similarly for null-terminated strings:
enable_dma_write();
write_string(address, "Hello World");
enable_dma_read();
char message[64]; // memory to read into; may be any size, but using 64 bytes here
read_string(address, message); // reads up to 64 characters, including null-terminator
Serial.println(message);
disable_dma();