4

Serial Diagnostic Link

A serial diagnostic link via the SPI bus provides the means

to clock fault data in and out of the fault register to the micro-

controller. When the microcontroller receives an INT inter-

rupt signal, data is clocked from the Serial Diagnostic

Register to determine what fault bit has been set. Appropri-

ate action for the fault may then be taken, as defined by the

programming of the microcontroller.

Serial Diagnostic Register

Fault bits consist of one OT bit and one OL bit for each

switching channel (A, B, C and D). Data is transferred out

of SO MSB first on the rising edge of SCK after CS goes

low. Data is shifted into the input shift register on the falling

edge of SCK. The defined order of the DO0 to DO7 fault

bits is as follows:

HIP0060 devices may be linked in cascade for the purposes

of SPI control. Serial data is clocked in and out of each

HIP0060 and then back to the host microcontroller. All linked

devices have a common control sequence. When CS goes

low, fault data is shifted to the Serial Diagnostic Register.

SCK must be low when CS goes low. Also, when CS goes

low, SO changes from a three-state to a low state and

remains low until SCK goes high. Serial data is transferred

by SCK. After the serial data is transferred, SCK must

remain low as CS goes high. The serial data transfer must

be a continuous sequence while CS is low.

Serial Peripheral Interface

The Serial Peripheral Interface (SPI) bus is system con-

trolled by a host micro. The SPI bus controls the Serial Diag-

nostic Link with the CS (Chip Select), SCK, SI, SO and RST

(Reset) lines. Figures 4 and 5 define the timing and protocol

for the bus.

Reset Operation

The RST input is an active low reset input. When RST is low,

the internal diagnostic flags are cleared but not the shift reg-

ister. When RST is low, all outputs and output switches are

disabled. To clear the shift register, CS is switched from high

to low during or after a reset while there are no active faults,

jamming data from the cleared fault flags into the shift regis-

tor. The RST input has an internal pull-up to sustain a logic

high when floating.

threshold, the output drivers are shutoff. To insure that the

BIT

NAME

CONDITION REQUIRED TO SET BIT

DO0

OTA

DO1

OTB

DO2

OTC

DO3

OTD

DO4

OLA

DO5

OLB

DO6

OLC

DO7

OLD

FIGURE 1. TYPICAL HIP0060 APPLICATION AS A LOW SIDE SWITCH FOR INDUCTIVE LOADS, LAMPS AND SMALL LINEAR

MOTORS OR STEPPER MOTORS

OUTA

OUTB

RELAY

SOLENOID

+5V

HIP0060

INA

INC

RST

4.7k

Ω

INT

IND

INB

OUTC

OUTD

LAMP

MOTOR

M

HIP0060