Manley Labs switch/hub - Manual (Page 8)

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