ASI4U datasheet(32/71 Pages) RENESAS

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ASI4U / ASI4U-E / ASI4U-F Datasheet

January 26, 2016

Figure 4.3

Timing Diagram Parameter Ports P[3:0] and PST

PST

tSetup

tPST

Parameter port output data

Keep stable

Parameter port input data

Data remains constant

if Multiplex_Parameter

flag is not set

Hi-Z if Multiplex_Parameter

flag is set

tPI-latch

min

max

thold

P[3:0]

4.6.2.

Parameter Multiplex Mode

The AS-Interface Complete Specification V3.0 defines a Parameter Multiplex Mode. This added feature allows bi-

directional data transfer through the parameter port. The bi-directionality is achieved by turning the Parameter

Output Drivers off after the Parameter Strobe period and before the input sampling event. By turning off its output

drivers during the Parameter Strobe pulse, an external microcontroller can read the data from the Parameter Port

of the ASI4U/ASI4U-E/ASI4U-F, prepare new return data, and place it to the port immediately after the Parameter

Strobe signal.

The Parameter Multiplex Mode becomes activated by setting the corresponding Multiplex_Parameter flag (=1) in

the EEPROM.

To keep full compatibility to A²SI-based applications, this flag should be kept as zero (=0). The A²SI did not allow

real bi-directional parameter data transfer since it was not able to turn the output drivers off. The return value to a

Write_Parameter call was always a wired AND combination of the output signal of the IC and the signal driven to

the port by the external logic.

4.6.3.

Special Function of P0, P1 and P2

If the Watchdog_Active flag is not set (=0) but the P0_Watchdog_Activation flag is set (= 1, in the Firmware Area

block of the EEPROM), the value of the Parameter Port signal P0 determines whether the communication

watchdog is enabled or disabled. In compliance with Slave Profile 7D-5, the behavior is defined as follows:

INPUT VALUE AT P0

STATE OF COMMUNICATION WATCHDOG

LOW level (=0)

Disabled

HIGH level (=1)

Enabled

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