Microcontroller Hardware Interfacing with Peripheral devices
Microcontroller interfacing with Program Memory
Figure shows interface of microcontroller 80c320 with program memory. (EA) pin is either connected with Vcc or Vss based on either internal ROM or external ROM is used to access the code. If the pin is connected to Vss than all the program or code fetches are directed to external ROM connected. (PSEN) signal is used as read strobe for external ROM. It is not activated for internal code fetches.
Microcontroller interfacing with Data Memory
Figure shows microcontroller interface with external RAM (DS1230Y). Here Port0 acts as multiplexed address/data bus to the RAM. The three lines of Port2 are used to page the RAM. The CPU generates read and write signals required to access external RAM.