ATmega1281R231 Atmel Corporation, ATmega1281R231 Datasheet - Page 32

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ATmega1281R231

Manufacturer Part Number
ATmega1281R231
Description
Manufacturer
Atmel Corporation
Datasheets

Specifications of ATmega1281R231

Flash (kbytes)
128 Kbytes
Max. Operating Frequency
16 MHz
Max I/o Pins
54
Spi
3
Twi (i2c)
1
Uart
2
Adc Channels
8
Adc Resolution (bits)
10
Adc Speed (ksps)
15
Analog Comparators
1
Crypto Engine
AES
Sram (kbytes)
8
Eeprom (bytes)
4096
Operating Voltage (vcc)
1.8 to 3.6
Timers
6
Frequency Band
2.4 GHz
Max Data Rate (mb/s)
2
Antenna Diversity
Yes
External Pa Control
Yes
Power Output (dbm)
3
Receiver Sensitivity (dbm)
-101
Receive Current Consumption (ma)
13.2
Transmit Current Consumption (ma)
14.4
Link Budget (dbm)
104
11.12 ATmega2560 rev. A
2549NS–AVR–05/11
1.
2. Part does not work under 2.4 volts
3. Incorrect ADC reading in differential mode
4. Internal ADC reference has too low value
5. IN/OUT instructions may be executed twice when Stack is in external RAM
Non-Read-While-Write area of flash not functional
Part does not work under 2.4 volts
Incorrect ADC reading in differential mode
Internal ADC reference has too low value
IN/OUT instructions may be executed twice when Stack is in external RAM
EEPROM read from application code does not work in Lock Bit Mode 3
The Non-Read-While-Write area of the flash is not working as expected. The problem is
related to the speed of the part when reading the flash of this area.
Problem Fix/Workaround
- Only use the first 248K of the flash.
- If boot functionality is needed, run the code in the Non-Read-While-Write area at maximum
1/4th of the maximum frequency of the device at any given voltage. This is done by writing
the CLKPR register before entering the boot section of the code.
The part does not execute code correctly below 2.4 volts.
Problem Fix/Workaround
Do not use the part at voltages below 2.4 volts.
The ADC has high noise in differential mode. It can give up to 7 LSB error.
Problem Fix/Workaround
Use only the 7 MSB of the result when using the ADC in differential mode.
The internal ADC reference has a value lower than specified.
Problem Fix/Workaround
- Use AVCC or external reference.
- The actual value of the reference can be measured by applying a known voltage to the
ADC when using the internal reference. The result when doing later conversions can then be
calibrated.
If either an IN or an OUT instruction is executed directly before an interrupt occurs and the
stack pointer is located in external ram, the instruction will be executed twice. In some cases
this will cause a problem, for example:
- If reading SREG it will appear that the I-flag is cleared.
- If writing to the PIN registers, the port will toggle twice.
- If reading registers with interrupt flags, the flags will appear to be cleared.
Non-Read-While-Write area of flash not functional
ATmega640/1280/1281/2560/2561
32

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