MC68HC05C9A Datasheet, PDF (117/124 Pages) Freescale Semiconductor, Inc – Microcontrollers

Appendix C
Self-Check Mode
C.1 Introduction
This appendix describes the self-check mode.
C.2 Self-Check Mode
Self-check mode is entered upon the rising edge of RESET if the IRQ pin is at V_tst and the TCAP pin is
at logic 1.
C.2.1 Self-Check Tests
The self-check read-only memory (ROM) at mask ROM location $3F00–$3FEF determines if the
microcontroller unit (MCU) is functioning properly.
These tests are performed:
1. Input/output (I/O) — Functional test of ports A, B, and C
2. Random-access memory (RAM) — Counter test for each RAM byte
3. Timer — Test of counter register and OCF bit
4. Serial communications interface (SCI) — Transmission test; checks for RDRF, TDRE, TC, and FE
flags
5. ROM — Exclusive OR with odd ones parity result
6. Serial peripheral interface (SPI) — Transmission test; checks for SPIF and WCOL flags
The self-check circuit is shown in Figure C-1.
MC68HC05C9A Advance Information Data Sheet, Rev. 5.1
Freescale Semiconductor
117