ATMEGA128RFA1-ZU Atmel, ATMEGA128RFA1-ZU Datasheet - Page 154

• Manufacturer Part Number: ATMEGA128RFA1-ZU
• Description: IC AVR MCU 2.4GHZ XCEIVER 64QFN
• Manufacturer: Atmel
• Series: ATMEGAr

Specifications of ATMEGA128RFA1-ZU

• Frequency: 2.4GHz
• Data Rate - Maximum: 2Mbps
• Modulation Or Protocol: 802.15.4 Zigbee
• Applications: General Purpose
• Power - Output: 3.5dBm
• Sensitivity: -100dBm
• Voltage - Supply: 1.8 V ~ 3.6 V
• Current - Receiving: 12.5mA
• Current - Transmitting: 14.5mA
• Data Interface: PCB, Surface Mount
• Memory Size: 128kB Flash, 4kB EEPROM, 16kB RAM
• Antenna Connector: PCB, Surface Mount
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 64-VFQFN, Exposed Pad
• Rf Ic Case Style: QFN
• No. Of Pins: 64
• Supply Voltage Range: 1.8V To 3.6V
• Operating Temperature Range: -40°C To +85°C
• Svhc: No SVHC (15-Dec-2010)
• Rohs Compliant: Yes
• Processor Series: ATMEGA128x
• Core: AVR8
• Data Bus Width: 8 bit
• Program Memory Type: Flash
• Program Memory Size: 128 KB
• Data Ram Size: 16 KB
• Interface Type: JTAG
• Maximum Clock Frequency: 16 MHz
• Number Of Programmable I/os: 38
• Number Of Timers: 6
• Operating Supply Voltage: 1.8 V to 3.6 V
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• 3rd Party Development Tools: EWAVR, EWAVR-BL
• Development Tools By Supplier: ATAVR128RFA1-EK1
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

11.11 Register Description
11.11.1 OSCCAL – Oscillator Calibration Value
154
ATmega128RFA1
possible to determine the state of the prescaler - even if it were readable. The exact
time it takes to switch from one clock division to another cannot be exactly predicted.
From the time the CLKPS values are written, it takes between t
the new clock frequency is active. In this interval 2 active clock edges are produced.
Here t
prescaler setting.
To avoid unintentional changes of clock frequency, a special write procedure must be
followed to change the CLKPS bits:
1. Write the Clock Prescaler Change Enable (CLKPCE) bit to one and all other bits in
2. Within four cycles, write the desired value to CLKPS while writing a zero to
Interrupts must be disabled when changing prescaler settings to make sure the write
procedure is not interrupted.
It is not required to change the prescaler setting of an existing software package written
for an 8MHz internal RC oscillator. The change of the prescaler (additional 1:2 divider)
is compensated by doubling the RC oscillator frequency of the ATmega128RFA1.
The Oscillator Calibration Register is used to trim the Calibrated Internal RC Oscillator
to remove process variations from the oscillator frequency. A preprogrammed
calibration value is automatically written to this register during chip reset, giving the
Factory calibrated frequency. The application software can write this register to change
the oscillator frequency. The oscillator can be calibrated to frequencies as specified in
the section "Electrical Characteristics". Calibration outside that range is not guaranteed.
Note that this oscillator is used to time EEPROM and Flash write accesses and these
write times will be affected accordingly. The calibration to very high frequencies can
cause EEPROM or Flash erase/write failures. The CAL7 bit determines the range of
operation for the oscillator. Setting this bit to 0 gives the lowest frequency range, setting
this bit to 1 gives the highest frequency range. The two frequency ranges are
overlapping, in other words a setting of OSCCAL = 0x7F gives a higher frequency than
OSCCAL = 0x80. The CAL6..0 bits are used to tune the frequency within the selected
range. A setting of 0x00 gives the lowest frequency in that range, and a setting of 0x7F
gives the highest frequency in the range.
• Bit 7:0 – CAL7:0 - Oscillator Calibration Tuning Value
Table 11-11 CAL Register Bits
Bit
NA ($66)
Read/Write
Initial Value
Register Bits
CAL7:0
CLKPR to zero.
CLKPCE.
1
is the previous clock period and t
CAL7
R/W
7
0
CAL6
R/W
6
0
CAL5
R/W
5
0
Value
0x00
0x80
0x7f
CAL4
R/W
4
0
2
is the clock period corresponding to the new
Description
Calibration value for lowest oscillator
frequency
End value of low frequency range calibration
Start value of high frequency range
calibration
CAL3
R/W
3
0
CAL2
R/W
2
0
CAL1
R/W
1
1
0
+ t
2
8266B-MCU Wireless-03/11
and t
CAL0
R/W
0
0
1
+ 2t
OSCCAL
2
before