AN1177 STMicroelectronics, AN1177 Datasheet - Page 3

• Manufacturer Part Number: AN1177
• Description: P51XA-PSD8XX DESIGN GUIDE
• Manufacturer: STMicroelectronics

a second alternate Flash memory to hold the IAP loader code and general data, and more SRAM. All three
of these memories can operate independently and concurrently; meaning the MCU can operate from one
memory while erasing/writing the other. This allows the MCU to continue normal operation during IAP,
which is crucial for some applications. This system also has programmable logic, expanded I/O, and de-
sign security. The two-chip solution is 100% programmable in the factory or in the field.
Figure 2. Embedded Flash System Capable of ISP (2 devices)
Note: 1. Other members of the PSD8XX family offer more Flash memory and more SRAM.
By design, the IAP method described above requires MCU participation to exercise a communication
channel to implement a download to the main Flash memory. The PSD8XX also offers an alternative
method called In-System Programming (ISP) to program the PSD using a built-in IEEE 1149.1 JTAG in-
terface requiring no MCU participation. This means that a completely blank PSD can be soldered into
place and the entire chip can be programmed in-system in just a few seconds using ST’s FlashLINK™
JTAG cable and PSDsoft Express development software. No P51XA firmware needs to be written. Just
plug in the FlashLINK cable to your PC’s parallel port and begin programming memory, logic, and config-
uration. This is a powerful feature of the PSD8XX that allows immediate development of application code
in your lab, smart manufacturing techniques, and easy field updates.
The FlashLINK™ cable and PSDsoft Express software are available in a kit from the website www.st.com/
psd .
Figure 3 gives a block diagram of the PSD813F for your reference.
2. Only the PSD813F1 offers EEPROM, while the other members of the PSD8XX family offer secondary Flash memory.
Computer
Host
Communication
Channel
Embedded System
P51XA
128 KByte Flash
Optional 32 KByte
Optional 2KByte SRAM
Programmable Logic
I/O
PSD813F
EEPROM/Flash
AN1177 - APPLICATION NOTE
1,2
System
I/O
JTAG
AI03327B
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