33892

MOTOROLA ANALOG INTEGRATED CIRCUIT DEVICE DATA

18

Figure 7. Single 16-Bit Word SPI Communication

Serial Input Communication

SPI communication is accomplished using 16-bit messages.

A message is transmitted by the MCU starting with the MSB

D15 and ending with the LSB, D0 (Table 1). Each incoming

command message on the SI terminal can be interpreted using

the following bit assignments: the MSB, D15, is the watchdog

bit. In some cases, output channel selection is done with bits

D12–D11. The next three bits, D10–D8, are used to select the

command register. The remaining five bits, D4–D0, are used to

configure and control the outputs and their protection features.

Multiple messages can be transmitted in succession to

accommodate those applications where daisy chaining is

desirable, or to confirm transmitted data, as long as the

messages are all multiples of 16 bits. Any attempt made to latch

in a message that is not 16 bits will be ignored.

The 33892 has defined registers, which are used to

configure the device and to control the state of the outputs.

Table 2, page 19, summarizes the SI registers.

CS

CSB

SI

SCLK

SO

D15

D1

D2

D3

D4

D5

D6

D7

D8

D9

D14

D13

D12

D11

D10

OD12

D0

OD13

OD14

OD15

OD6

OD7

OD8

OD9

OD10

OD11

OD1

OD2

OD3

OD4

OD5

1.

RSTB is in a logic H state during the above operation.

2.

DO, D1, D2, ... , and D15 relate to the most recent ordered entry of program data into the LUX IC

3.

OD0, OD1, OD2, ..., and OD15 relate to the first 16 bits of ordered fault and status data out of the LUX IC

NOTES:

OD0

CS

device.

device.

1. RST is a logic [1] state during the above operation.

2. D15–D0 relate to the most recent ordered entry of data into the device.

3. OD15–OD0 relate to the first 16 bits of ordered fault and status data out of the device.

Notes

Table 1. SI Message Bit Assignment

Bit Sig SI Msg Bit

Message Bit Description

MSB

D15

Watchdog in: toggled to satisfy watchdog

requirements.

D14–D15

Not used.

D12–D11

Register address bits used in some cases for

output channel selection.

D10–D8

Register address bits.

D7–D5

Not used.

D4–D1

Used to configure the inputs, outputs, and the

device protection features and SO status

content.

LSB

D0

Used to configure the inputs, outputs, and the

device protection features and SO status

content.

Freescale Semiconductor, Inc.

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