AT89LP428 Atmel Corporation, AT89LP428 Datasheet - Page 114

• Manufacturer Part Number: AT89LP428
• Manufacturer: Atmel Corporation

Specifications of AT89LP428

• Flash (kbytes): 4 Kbytes
• Max. Operating Frequency: 25 MHz
• Cpu: 8051-1C
• Max I/o Pins: 30
• Spi: 1
• Uart: 1
• Sram (kbytes): 0.75
• Eeprom (bytes): 512
• Self Program Memory: IAP
• Operating Voltage (vcc): 2.4 to 5.5
• Timers: 3
• Isp: SPI/OCD
• Watchdog: Yes

22.2
22.3
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Software Breakpoints
Limitations of On-chip Debug
AT89LP428/828
Figure 22-1. AT89LP428/828 On-chip Debug Connections
The AT89LP428/828 microcontroller includes a BREAK instruction for implementing program
memory breakpoints in software. A software breakpoint can be inserted manually by placing the
BREAK instruction in the program code. Some emulator systems may allow for automatic inser-
tion/deletion of software breakpoints. The Flash memory must be re-programmed each time a
software breakpoint is changed. Frequent insertions/deletions of software breakpoints will
reduce the endurance of the nonvolatile memory. Devices used for debugging purposes should
not be shipped to end customers. The BREAK instruction is treated as a two-cycle NOP when
OCD is disabled.
The AT89LP428/828 is a fully-featured microcontroller that multiplexes several functions on its
limited I/O pins. Some device functionality must be sacrificed to provide resources for On-chip
Debugging. The On-chip Debug System has the following limitations:
• The Debug Clock pin (DCL) is physically located on that same pin as Port Pin P3.6 and the
• When using the Internal RC Oscillator during debug, DDA is located on the XTAL1/P4.0 pin.
• When using the External Clock during debug, DDA is located on the XTAL2/P4.1 pin and the
• When using the Crystal Oscillator during debug, DDA is located on the P3.7 pin and the
External Reset (RST). Therefore, neither P3.6 nor an external reset source may be emulated
when OCD is enabled.
The P4.0 I/O function cannot be emulated in this mode.
system clock drives XTAL1/P4.0. The P4.1 I/O and CLKOUT functions cannot be emulated in
this mode.
crystal connects to XTAL1/P4.0 and XTAL2/P4.1. The P3.6 I/O function cannot be emulated
in this mode.
DDA
DCL
P3.6/RST
XTAL1
GND
CLK = Internal RC
A
DCL
VCC
CLK = Crystal Oscillator
P3.6/RST
XTAL2
XTAL1
GND
C
DCL
CLK
VCC
P3.7
CLK = External Clock
P3.6/RST
XTAL1
GND
DDA
B
XTAL2
VCC
3654A–MICRO–8/09
DDA