STMicroelectronics switch/hub Brochure page 8

Remote Field Updates with IAP
Remote Field Updates with IAP
1. Before IAP
READ & READ &
WRITE WRITE
2 2 2 2
8032 8032
8032 8032
MCU MCU
MCU MCU
READ READ READ
ONLY ONLY ONLY
• MCU reading program
from Main Flash
USB, UART,
2
I C, Modem...
Updated
Updated
Program
Program
www.st.com/micropsd
• 8051s typically cannot write to "code" space
–
nd nd nd nd
Flash Flash Flash Flash
• Typical Flash memory cannot be read and written
DATA DATA
DATA DATA
at the same time
–
MAIN MAIN
MAIN MAIN
FLASH FLASH
FLASH FLASH
–
OLD OLD
OLD OLD
2. During IAP
CODE CODE
CODE CODE
READ & READ & READ &
8032 8032
8032 8032
MCU MCU READ & READ & READ &
MCU MCU
• Special Register temporarily re-
classifies Main Flash as Data
• MCU now reads IAP program
nd
from 2 Flash while receiving
bytes of new program from
USB, UART, Modem, I
and writes the new program to
Main Flash
Special µPSD register eliminates this limitation
Dual Banks of Flash eliminate this limitation
Read program from one bank while writing to the other bank
WRITE WRITE WRITE
nd nd nd nd
2 2 2 2 Flash Flash Flash Flash
CODE CODE
CODE CODE
READ READ READ
ONLY ONLY ONLY
MAIN MAIN MAIN MAIN
FLASH FLASH
FLASH FLASH
WRITE WRITE WRITE
TREAT TREAT
TREAT TREAT
AS DATA AS DATA
AS DATA AS DATA
READ READ READ
ONLY ONLY ONLY
2
C, etc.
• Special Register classifies
Main Flash as Code again
• MCU now reading new
program from Main Flash
3. After IAP
READ & READ &
WRITE WRITE
nd nd nd nd
2 2 2 2 Flash Flash Flash Flash
DATA DATA
DATA DATA
8032 8032
8032 8032
MAIN MAIN
MAIN MAIN
MCU MCU MCU MCU
FLASH FLASH FLASH FLASH
NEW NEW NEW
NEW NEW NEW
CODE CODE CODE
CODE CODE CODE
READ READ READ
ONLY ONLY ONLY
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