DS89C420-QCL Datasheet, PDF (132/139 Pages) Maxim Integrated Products – Ultra-High-Speed Flash Microcontroller User’s Guide

Ultra-High-Speed Flash
Microcontroller User’s Guide
PROGRAM EXECUTION
INTERNAL MEMORY DISABLED EA\ =0
INTERNAL MEMORY ENABLED EA\ =1
N
RST = 1
Y
EA = 0
N
DEVICE IN RESET
(INTERNAL MEMORY ENABLED)
Y
PSEN = 0
N
DEVICE IN RESET
(INTERNAL MEMORY DISABLED)
Y
AUTOBAUD ROUTINE
AWAITING <CR> CHARACTER ON RXD OF SERIAL PORT 0
SERIAL COMMUNICATION WITH THE ROM LOADER CAN
PROCEED AS ESTABLISHED ON SERIAL PORT 0
N
Y
PSEN
TOGGLED 0 ¹
N
Y
POWER-ON
RESET
Figure 15-1. Invoking and Exiting the Loader on the Ultra-High-Speed Flash Microcontroller
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