Rainbow Electronics T89C5121 - Manual (Page 64)

64
A/T8xC5121
4164G–SCR–07/06
Figure 26. Hardware in Relation with the Two Communication Protocols
EEPROM Mapping The 16K Bytes EEPROM mapping is the following:
The three last bytes are reserved respectively:
• Software Security Byte: address 3FFDh
• CRC Bytes: address 3FFEh and 3FFFh
The use of these bytes is described in the following paragraphs.
Therefore, the User Program must be mapped from 0000h to 3FFCh address.
EEPROM external
TWI
DV
CC
or Ext. V
CC
(3V)
Internal EEPROM
AT24C128
V
CC
V
SS
DV
CC
or Ext.V
CC
(3V)
A0 = A1 = 0
wp = 0
SDA
SCL
TWI
Optional
Thanks to internal pull-ups
DV
CC
V
CC
P2.1
P2.0
(A0 = 1,A1 = 0)
DVss Wp = 1
AT24C128
(default values if not tied)
P3.2/INT0
UART
BOOTLOADER
Address = 01h
Address = 00h
ISP Software Tool
SDA
SCL
P3.7/CRST1
3FFD
3FFE
3FFF
0000h
Reserved address