ATTINY25-20SUR Atmel, ATTINY25-20SUR Datasheet - Page 144

• Manufacturer Part Number: ATTINY25-20SUR
• Description: MCU AVR 2KB FLASH 20MHZ 8SOIC
• Manufacturer: Atmel
• Series: AVR® ATtinyr

Specifications of ATTINY25-20SUR

• Core Processor: AVR
• Core Size: 8-Bit
• Speed: 20MHz
• Connectivity: USI
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 6
• Program Memory Size: 2KB (1K x 16)
• Program Memory Type: FLASH
• Eeprom Size: 128 x 8
• Ram Size: 128 x 8
• Voltage - Supply (vcc/vdd): 2.7 V ~ 5.5 V
• Data Converters: A/D 4x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: *
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

18.4
18.5
18.6
18.6.1
144
Software Break Points
Limitations of debugWIRE
Register Description
ATtiny25/45/85
DWDR – debugWire Data Register
When designing a system where debugWIRE will be used, the following observations must be
made for correct operation:
debugWIRE supports Program memory Break Points by the AVR Break instruction. Setting a
Break Point in AVR Studio
tion replaced by the BREAK instruction will be stored. When program execution is continued, the
stored instruction will be executed before continuing from the Program memory. A break can be
inserted manually by putting the BREAK instruction in the program.
The Flash must be re-programmed each time a Break Point is changed. This is automatically
handled by AVR Studio through the debugWIRE interface. The use of Break Points will therefore
reduce the Flash Data retention. Devices used for debugging purposes should not be shipped to
end customers.
The debugWIRE communication pin (dW) is physically located on the same pin as External
Reset (RESET). An External Reset source is therefore not supported when the debugWIRE is
enabled.
The debugWIRE system accurately emulates all I/O functions when running at full speed, i.e.,
when the program in the CPU is running. When the CPU is stopped, care must be taken while
accessing some of the I/O Registers via the debugger (AVR Studio).
A programmed DWEN Fuse enables some parts of the clock system to be running in all sleep
modes. This will increase the power consumption while in sleep. Thus, the DWEN Fuse should
be disabled when debugWire is not used.
In Asynchronous Mode and in ATtiny15 Compatibility Mode, Timer/Counter1 is running freely
and cannot be single-stepped by the debugger.
The following section describes the registers used with the debugWire.
The DWDR Register provides a communication channel from the running program in the MCU
to the debugger. This register is only accessible by the debugWIRE and can therefore not be
used as a general purpose register in the normal operations.
Bit
0x22
Read/Write
Initial Value
• Pull-Up resistor on the dW/(RESET) line must be in the range of 10k to 20 kΩ. However, the
• Connecting the RESET pin directly to V
• Capacitors inserted on the RESET pin must be disconnected when using debugWire.
• All external reset sources must be disconnected.
pull-up resistor is optional.
DWDR7
R/W
7
0
DWDR6
R/W
®
6
0
will insert a BREAK instruction in the Program memory. The instruc-
DWDR5
R/W
5
0
DWDR4
CC
R/W
4
0
will not work.
DWDR3
R/W
3
0
DWDR2
R/W
2
0
DWDR1
R/W
1
0
DWDR0
R/W
0
0
2586M–AVR–07/10
DWDR