AT89C5131A-L Atmel Corporation, AT89C5131A-L Datasheet - Page 46

• Manufacturer Part Number: AT89C5131A-L
• Manufacturer: Atmel Corporation

Specifications of AT89C5131A-L

• Flash (kbytes): 32 Kbytes
• Max. Operating Frequency: 48 MHz
• Cpu: 8051-12C
• Max I/o Pins: 34
• Usb Transceiver: 1
• Usb Speed: Full Speed
• Usb Interface: Device
• Spi: 1
• Twi (i2c): 1
• Uart: 1
• Sram (kbytes): 1.25
• Eeprom (bytes): 1024
• Self Program Memory: API
• Operating Voltage (vcc): 3.0 to 3.6
• Timers: 4
• Isp: UART/USB
• Watchdog: Yes

Low Pin Count Hardware
Conditions (SOIC28)
46
AT89C5131A-L
As PSEN is an output port in normal operating mode (running user application or boot-
loader code) after reset, it is recommended to release PSEN after rising edge of reset
signal.
Low pin count products do not have PSEN signal, thus for these products, the boot-
loader is always executed after reset thanks to the BLJB bit. The Hardware Conditions
are detected at the begining of the bootloader execution from reset.
The default factory Hardware Condition is assigned to port P1.
•
In order to offer the best flexibility, the user can define its own Hardware Condition on
one of the following Ports:
•
•
•
The Hardware Conditions configuration is stored in three bytes called P1_CF, P3_CF,
P4_CF.
These bytes can be modified by the user through a set of API or through an ISP
command.
Note:
See a detailed description in the applicable Document.
P1 must be equal to FEh
Port1
Port3
Port4 (only bit0 and bit1)
–
1. The BLJB must be at 0 (programmed) to be able to restart the bootloader.
2. BLJB can always be changed by the means of API, whether it's a low or high pin
Datasheet Bootloader USB AT89C5131.
count package.But for a low pin count version, if BLJB=1, no ISP via the Bootloader
is further possible (because the HW conditions are never evaluated, as described in
the USB Bootloader Datasheet). To go back to ISP, BLJB needs to be changed by a
parallel programmer(or by the APIs).
4338F–USB–08/07