MC68HC05B6_13 Datasheet, PDF (155/302 Pages) Freescale Semiconductor, Inc – Microcontrollers

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 PC0–PC3 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 V_DD dc (via a 4.7kΩ resistor) to the IRQ pin and 5V dc input (via a 4.7kΩ
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 flashing LEDs; a bad device will be indicated by the LEDs holding at one value.
Note: Self-check code can be obtained from your local Freescale representative.
I/0 —
RAM —
ROM —
Timer —
SCI —
A/D —
PLM —
Interrupts —
Watchdog—
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
flags
Transmission test; check for RDRF, TDRE, TC and FE flags
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 firmware in the non-user ROM areas of
the MC68HC05B6 and related devices.
As these firmware routines are intended primarily to help Freescale’s engineers test the
devices, they may be changed or removed at any time.
For this reason, Freescale 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. 4.1
MC68HC05B4
Freescale
A-5