MC68HC05B4 Datasheet, PDF(155/298 Page) Motorola, Inc – High-density Complementary Metal Oxide Semiconductor (HCMOS) Microcomputer Unit

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MC68HC05B4 Datasheet, PDF (155/298 Pages) Motorola, Inc – High-density Complementary Metal Oxide Semiconductor (HCMOS) Microcomputer Unit

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A.2

Self-check mode

The self-check function available on the MC68HC05B4 provides an internal capability to determine

if the device is functional. Self-check is performed using the circuit shown in Figure A-3. Port C

pins PC0âPC3 are monitored for the self-check results (light emitting diodes are shown but other

devices could be used), and are interpreted as described in Table A-3. The self-check mode is

entered by applying 2 x VDD dc (via a 4.7kâ¦ resistor) to the IRQ pin and 5V dc input (via a 4.7kâ¦

resistor) to the TCAP1 pin and then depressing the reset switch to execute a reset. After reset, the

following tests are performed automatically and once completed they continually repeat. A good

device will exhibit ï¬ashing LEDs; a bad device will be indicated by the LEDs holding at one value.

Note: Self-check code can be obtained from your local Motorola representative.

I/0 â

RAM â

ROM â

Timer â

SCI â

A/D â

PLM â

Interrupts â

Watchdogâ

Functionally exercises ports A, B, C and D

Counter test for each RAM byte

Exclusive OR with odd ones parity result

Tracks counter registers and checks ICF1, ICF2, OCF1, OCF2 and TOF

ï¬ags

Transmission test; check for RDRF, TDRE, TC and FE ï¬ags

Check A/D functionality on internal channels: VRL, VRH and (VRL +

VRH)/2

Checks the PLM basic functionality

Tests external timer and SCI interrupts

Tests the watchdog

Caution: This document includes descriptions of the various self-check and bootstrap

mechanisms that are currently implemented as ï¬rmware in the non-user ROM areas of

the MC68HC05B6 and related devices.

As these ï¬rmware routines are intended primarily to help Motorolaâs engineers test the

devices, they may be changed or removed at any time.

For this reason, Motorola recommends the self-check and bootstrap routines are not

called from the user software. Customers who do call these routines from the user

software do so at their own risk.

14

MC68HC05B6

Rev. 4

MC68HC05B4

TPG

MOTOROLA

A-5

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