sak-c868p-1rr Infineon Technologies Corporation, sak-c868p-1rr Datasheet - Page 231

• Manufacturer Part Number: sak-c868p-1rr
• Description: 8 - Bit Cmos Microcontroller
• Manufacturer: Infineon Technologies Corporation

9
The C868, includes a bootstrap mode, which is activated by setting the ALE/BSL pin at
logic low with a pulldown and TxD pin at logic high with a pullup at the rising edge of the
RESET. Or it can be entered by software, that is by setting BSLEN bit and resetting
SWAP bit in SFR SYSCON1 accompany by an unlock sequence, the details can be
found in
In the bootstrap mode, software routines of the bootstrap loader located in the boot ROM
will be executed. Its purpose is to allow the easy and quick programming of the internal
SRAM (0000
the MCU is in-circuit. It also provides a way to program SRAM or XRAM through
bootstrapping from an external SPI or I2C EEPROM.
The first action of the bootstrap loader is to detect the presence of EEPROM and its type,
SPI or I2C, and check the first byte of the serial EEPROM. If the first byte is 0A5
MCU would enter Phase A to download from the EEPROM. Otherwise, it will enter
Phase B to establish a serial communication with the connected host. Bootstrapping
from the serial EEPROM can also be done in phase B if it is invoked by the host.
Figure 9-1
User’s Manual
Load custom code
Bootstrap
EEPROM
Phase A
Activate mode 0
to SRAM/XRAM
serial
from
Chapter
The Bootstrap Loader
H
Yes
The phases of the Bootstrap Loader
to 1FFF
3.3.2.
EEPROM (first byte)
program in XRAM
H
Activate Mode 1
Execute custom
Read serial
) or XRAM (FF00
byte=A5
Start
H
?
program in SRAM
Init serial interface 0
Activate Mode 2
Execute custom
and synchronize to
the host baud rate
H
Receive header
9-1
block from host
No
Select working
to FFFF
Phase B
mode
H
) via serial interface (UART) while
Load program from SPI serial
EEPROM to SRAM/XRAM
Activate Mode 3
The Bootstrap Loader
Phase B, Phase II
Phase B, Phase I
I2C serial EEPROM
Load program from
Activate Mode 4
to SRAM/XRAM
V 1.0, 2003-01
C868
H
, the