Datasheet

48
4337K–USB–04/08
AT89C5130A/31A-M
11.5 Hardware Conditions
It is possible to force the controller to execute the bootloader after a Reset with hardware condi-
tions. Depending on the product type (low pin count or high pin count package), there are two
methods to apply the hardware conditions.
11.5.1 High Pin Count Hardware Conditions (PLCC52, QFP64)
For high pin count packages, the hardware conditons (EA = 1, PSEN = 0) are sampled during
the RESET
rising edge to force the on-chip bootloader execution (See Figure 27-5 on page
172). 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 11-3 below).
Figure 11-3. ISP Hardware conditions
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.
To ensure correct microcontroller startup, the PSEN pin should not be tied to ground during
power-on (see
Figure 11-4 below).
Copy of the Device ID#3: Name and Revision FFh 61h
Description Default Value Address
ALE
EA
VCC
/PSEN
RST
GND
1K
Unconnected
VCC
VSS
VCC
GND
GND
C1
C2
Crystal
GND
XTAL2
XTAL1
Bootloader
GND