KMA220 datasheet(21/36 Pages) NXP

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KMA220

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Product data sheet

Rev. 1 — 24 May 2012

21 of 36

NXP Semiconductors

KMA220

Dual channel programmable angle sensor

13.3.2 Read access

Perform the following procedure, to read data from the sensor:

1. Start condition: The master drives a rising edge after a LOW level

2. Command: The master sends a read command (CMD0 = 1)

3. Handover: The master sends a handover bit, that is a logic 0 and disables the output

after a three-quarter bit period

4. Takeover: The slave drives a LOW level after the falling edge for ttko(slv)

5. Data: The slave sends two data bytes

6. Handover: The slave sends a handover bit, that is a logic 0 and disables the output

after a three-quarter bit period

7. Takeover: The master drives a LOW level after the falling edge for ttko(mas)

8. Stop condition: The master drives a rising edge after a LOW level

Figure 16 shows the read access of the digital interface. The signal OWI represents the

data on the bus from the master or slave. The signals: master output enable and slave

output enable indicate when the master or the slave output is enabled or disabled,

respectively.

(1) Duration of LOW level for slave takeover ttko(slv).

(2) The master output enable and the slave output enable overlap, because both drive a LOW level.

However this behavior ensures the independency from having a pull-up or pull-down on the bus. In

addition, it improves the EMC robustness, because all levels are actively driven.

(3) Duration of LOW level for master takeover ttko(mas).

(4) If the master does not take over, the pull-up generates the stop condition. Otherwise a time-out is

generated if there is a pull-down and the slave waits for a rising edge as start condition.

(5) If the master does not drive the bus, the bus-pull defines the bus.

Fig 16. OWI read access

001aag744

master

output

enable

slave

output

enable

START

CMD7

CMD0

RDATA0

(1)

(2)

(4)

(5)

(3)

HANDSHAKE

RDATA15

IDLE

STOP

OWI

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