AT89C5131A-L Atmel Corporation, AT89C5131A-L Datasheet - Page 5

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AT89C5131A-L

Manufacturer Part Number
AT89C5131A-L
Description
Manufacturer
Atmel Corporation
Datasheets

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
In-System
ISP allows the user to program or reprogram a microcontroller’s on-chip Flash memory through
the USB bus without removing it from the system and without the need of a pre-programmed
Programming
application.
This section describes how to start the USB bootloader and the higher level protocol over the
USB.
Boot Process
The bootloader can be activated in two ways:
Hardware conditions
Regular boot process
Figure 3 and Figure 4 describe the boot process flows for low pin count and high pin count
products.
High Pin Count
The Hardware conditions (EA = 1, PSEN = 0) during the RESET rising edge force the on-chip
Hardware Conditions
bootloader execution. In this way the bootloader can be carried out regardless of the user Flash
memory content. It is recommended to pull the PSEN pin down to ground though a 1K resistor to
prevent the PSEN pin from being damaged (see Figure 2 below).
Figure 2. ISP Hardware conditions
GND
As PSEN is an output port in normal operating mode (running user application or bootloader
code) after reset, it is recommended to release PSEN after rising edge of reset signal. The hard-
ware conditions are sampled at reset signal rising edge, thus they can be released at any time
when reset input is high.
Low Pin Count
The Hardware Condition forces the bootloader execution from reset.
Hardware Conditions
The default factory Hardware Condition is assigned to port P1.
P1 must be equal to FEh
In order to offer the best flexibility, the user can define its own Hardware Condition on one of the
following Ports:
Port1
4287E–USB–04/08
AT89C5131A USB Bootloader
VCC
VCC
VCC
EA
ALE
RST
XTAL2
Bootloader
XTAL1
/PSEN
1K
VSS
GND
GND
Unconnected
C2
GND
Crystal
GND
C1
5

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