This contains a simple 256 byte RAM implementation, done using derive(Chip) macro.
This exposes :
- 8 bit addr (address bus) in form of
u8 - 8 bit data (data bus) in form of
Option<u8> - 1 bit is_active (chip select) in form of bool
- 1 bit is_read (read/write) in form of bool
This takes 1 tick to store data, and 1 tick to put data on data bus into memory. Thus to read data, one will need two ticks - 1 tick where address is placed on the address bus, next tick the data will be available on the data bus. To write data, one will need to put data and address on respective buses, and in the next tick, it will be stored. See PCB to see an example of interfacing this.
To read the data :
- make is_active
true - make is_read
true - set addr as value of the memory location to read
- set data as
Some(_)this is so that the data bus will be un-tristated, any value will do, as it will be overwritten
In the next tick the data will be Some(data_at_mem_loc)
To store data :
- make is_active
true - make is_read
false - set addr as the memory location to store data at
- set data as Some(data) to be stored
In next tick, the data will be stored.