PSD813F1V Datasheet, PDF (56/110 Pages) STMicroelectronics – Flash In-System Programmable (ISP) Peripherals for 8-bit MCUs, 3.3V

PSD813F1V
Address In Mode
For microcontrollers that have more than 16 ad-
dress lines, the higher addresses can be connect-
ed to Port A, B, C, and D. The address input can
be latched in the Input Macrocell by the address
strobe (ALE/AS). Any input that is included in the
DPLD equations for the PLD’s Flash, EEPROM, or
SRAM is considered to be an address input.
Data Port Mode
Port A can be used as a data bus port for a micro-
controller with a non-multiplexed address/data
bus. The Data Port is connected to the data bus of
the microcontroller. The general I/O functions are
disabled in Port A if the port is configured as a
Data Port.
Peripheral I/O Mode
Peripheral I/O Mode can be used to interface with
external peripherals. In this mode, all of Port A
serves as a tri-stateable, bi-directional data buffer
for the microcontroller. Peripheral I/O Mode is en-
abled by setting Bit 7 of the VM Register to a ‘1.’
Figure 28 shows how Port A acts as a bi-direction-
al buffer for the microcontroller data bus if Periph-
eral I/O Mode is enabled. An equation for PSEL0
and/or PSEL1 must be written in PSDabel. The
buffer is tri-stated when PSEL 0 or PSEL1 is not
active.
Figure 28. Peripheral I/O Mode
RD
PSEL0
PSEL1
PSEL
VM REGISTER BIT 7
D0 - D7
DATA BUS
PA0 - PA7
WR
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