ATA6616-P3PW Atmel, ATA6616-P3PW Datasheet - Page 61

• Manufacturer Part Number: ATA6616-P3PW
• Description: TXRX MULTICHIP MOD LIN SIP 38QFN
• Manufacturer: Atmel
• Series: AVR® ATA66 LIN-SBCr

Specifications of ATA6616-P3PW

• Core Processor: AVR
• Core Size: 8-Bit
• Speed: 16MHz
• Connectivity: I²C, LIN, SPI, UART/USART, USI
• Peripherals: Brown-out Detect/Reset, POR, PWM, Temp Sensor, WDT
• Number Of I /o: 16
• Program Memory Size: 8KB (8K x 8)
• Program Memory Type: FLASH
• Eeprom Size: 512 x 8
• Ram Size: 512 x 8
• Voltage - Supply (vcc/vdd): 2.7 V ~ 5.5 V
• Data Converters: A/D 11x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 125°C
• Package / Case: 38-VQFN
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

4.5.4
4.5.4.1
4.5.4.2
4.5.5
4.5.5.1
9132D–AUTO–12/10
System Clock Prescaler
Register Description
Features
Switching Time
OSCCAL – Oscillator Calibration Register
The Atmel
– CLKPR. This feature can be used to decrease power consumption when the requirement for
processing power is low. This can be used with all clock source options, and it will affect the
clock frequency of the CPU and all synchronous peripherals. clk
are divided by a factor as shown in
When switching between prescaler settings, the System Clock Prescaler ensures that no
glitches occur in the clock system and that no intermediate frequency is higher than neither
the clock frequency corresponding to the previous setting, nor the clock frequency corre-
sponding to the new setting.
The ripple counter that implements the prescaler runs at the frequency of the undivided clock,
which may be faster than the CPU’s clock frequency. Hence, it is not possible to determine the
state of the prescaler – even if it were readable, and 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 T1 + T2 and T1 + 2*T2 before
the new clock frequency is active. In this interval, 2 active clock edges are produced. Here, T1
is the previous clock period, and T2 is the period corresponding to the new prescaler setting.
• Bits 7:0 – CAL7:0: Oscillator Calibration Value
The Oscillator Calibration Register is used to trim the Calibrated Internal RC Oscillator to
remove process variations from the oscillator frequency. The factory-calibrated value is auto-
matically written to this register during chip reset, giving an oscillator frequency of 8.0 MHz at
25°C. The application software can write this register to change the oscillator frequency. The
oscillator can be calibrated to any frequency in the range 7.3 - 8.1MHz within ±2% accuracy.
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. If the EEPROM or Flash are written, do not calibrate to
more than 8.8MHz. Otherwise, the EEPROM or Flash write may fail.
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 fre-
quency ranges are overlapping, in other words a setting of OSCCAL = 0x7F gives a higher
frequency than OSCCAL = 0x80.
Bit
Read/Write
Initial Value
®
ATtiny87/167 system clock can be divided by setting the Clock Prescaler Register
CAL7
R/W
7
CAL6
R/W
6
CAL5
R/W
5
Table 4-14 on page
Device Specific Calibration Value
CAL4
R/W
4
Atmel ATA6616/ATA6617
CAL3
R/W
3
63.
CAL2
R/W
2
I/O
, clk
CAL1
R/W
ADC
1
, clk
CAL0
CPU
R/W
0
, and clk
OSCCAL
FLASH
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