PSD813F1 datasheet(60/120 Pages) STMICROELECTRONICS

60 / 120 page

PSD813F1-A

Preliminary

The

PSD813F1

Functional

Blocks

(cont.)

9.4.2.4 Address In Mode

For microcontrollers that have more than 16 address lines, the higher addresses can be

connected to Port A, B, C, and D. The address input can be latched in the Input Micro

⇔Cell

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.

9.4.2.5 Data Port Mode

Port A can be used as a data bus port for a microcontroller 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.

9.4.2.6 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 enabled by setting Bit 7 of the VM Register to a ‘1’. Figure 25 shows how Port A

acts as a bi-directional buffer for the microcontroller data bus if Peripheral 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 1 is not active.

9.4.2.7 JTAG ISP

Port C is JTAG compliant, and can be used for In-System Programming (ISP). You can

multiplex JTAG operations with other functions on Port C because ISP is not performed

during normal system operation. For more information on the JTAG Port, refer to

section 9.6.

9.4.2.3 Address Out Mode

For microcontrollers with a multiplexed address/data bus, Address Out Mode can be used

to drive latched addresses onto the port pins. These port pins can, in turn, drive external

devices. Either the output enable or the corresponding bits of both the Direction Register

and Control Register must be set to a ‘1’ for pins to use Address Out Mode. This must be

done by the MCU at run-time. See Table 22 for the address output pin assignments on

Ports A and B for various MCUs.

For non-multiplexed 8 bit bus mode, address lines A[7:0] are available to Port B in Address

Out Mode.

Note: do not drive address lines with Address Out Mode to an external memory device if it

is intended for the MCU to boot from the external device. The MCU must first boot from

PSD memory so the Direction and Control register bits can be set.

Microcontroller

Port A (3:0)

Port A (7:4)

Port B (3:0)

Port B (7:4)

8051XA (8-Bit)

N/A*

Address (7:4)

Address (11:8)

N/A

80C251

N/A

Address (11:8)

Address (15:12)

(Page Mode)

All Other

Address (3:0)

Address (7:4)

Address (3:0)

Address (7:4)

8-Bit Multiplexed

8-Bit

N/A

Address [3:0]

Address [7:4]

Non-Multiplexed Bus

Table 22. I/O Port Latched Address Output Assignments

N/A = Not Applicable.

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