8051duino is an MCS-51 based arduino compatible PCB. It contains an 8XC51 CPU, a 27C256 compatible footprint for a FLASH or EEPROM memory chip and a 71256 narrow-dip SRAM. A jumper is provided to tie EA# to ground, this way you can use any 8051 chip (even the OTP ROM ones)
The aim of this board is to enable 8051 programming using a familiar format.
Part of the address and data bus (AD0-AD7, A8-A12, A15, WR#, RD#, ALE) is routed to the headers, as well as UART and 4 GPIOs. This allows to design HATs that contain any other bus compatible peripherals (such as UARTs, ADCs, IOs and even floppy disk controllers). External bus breaks out 12 address bits + A15.
| Space | device | |-------|--------| |Prog 0000 - 7FFF | ROM (32k) | |XDATA 0000 - 7FFF | SRAM (32k) | |XDATA 8000 - 9FFF | space for user peripherals (8k) |
The board uses a DC barrel jack input and a 7805 to provide 5V.
User LED is connected to P1.0.
Rev 1A is similar, except that it does not have external SRAM.