C511 datasheet(105/128 Pages) SIEMENS

105 / 128 page

Semiconductor Group

9-5

EEPROM Programming Interface

SAB-C513A-H

9.2.1 Selection of the Programming Mode

The programming mode is selected by applying specific logic levels to the four PMS0-3 pins of the

SAB-C513A-H.

Table 9-2

Programming Mode Selection Pins

Note that PMS3 has to be active (’1’) during the whole programming mode operation. During normal

operation PMS2 and PMS1 are outputs (PSEN, ALE) and no external driving circuitry should be

connected to these pins.

It should be also noted, that always a clock has to be supplied in programming mode and that the

operating voltage is restricted to 5 V

± 10%.

9.2.2 Resetting the Programming Interface

By applying a high level to the PRES pin the contents of the programming interface registers will be

set to their initial values. When entering the programming mode, PRES should be held high.

The programming interface must not be reset while programming or erasing the EEPROM (PROG

bit =1). The program or erase cycle should be finished properly before resetting the interface.

9.2.3 Interface Bus Operation

The programming interface with its registers can be accessed via a Intel type multiplexed bus

interface. Figures 9-9-4 and 9-9-5 illustrate a read and a write access to the registers. To enable

access to the programming interface the enable input PCS must be active during the entire access

cycle (from leading edge of ALE until trailing edge of RD or WR). PCS should always be deactivated

between subsequent accesses to the programming interface. With the falling edge of ALE the

address of the register to be accessed is latched. The read signal puts the contents of the selected

selected register. Each read and write cycle must be initiated by a PALE high pulse.

Mode

PMS3

(RESET)

PMS2

(PSEN)

PMS1

(ALE)

PMS0

(EA)

Normal Mode

1 or 0

none

0 or 1

Programming Mode

1010

C511 Datasheet(PDF) 105 Page - Siemens Semiconductor Group

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