ATMEGA162L-8MI Atmel, ATMEGA162L-8MI Datasheet - Page 26

• Manufacturer Part Number: ATMEGA162L-8MI
• Description: IC MCU AVR 16K 3V 8MHZ 44-QFN
• Manufacturer: Atmel
• Series: AVR® ATmegar

Specifications of ATMEGA162L-8MI

• Core Processor: AVR
• Core Size: 8-Bit
• Speed: 8MHz
• Connectivity: EBI/EMI, SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 35
• Program Memory Size: 16KB (8K x 16)
• Program Memory Type: FLASH
• Eeprom Size: 512 x 8
• Ram Size: 1K x 8
• Voltage - Supply (vcc/vdd): 2.7 V ~ 5.5 V
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 44-VQFN Exposed Pad
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Data Converters: -

Pull-up and Bus Keeper
Timing
26
ATmega162(V/U/L)
The pull-up resistors on the AD7:0 ports may be activated if the corresponding Port reg-
ister is written to one. To reduce power consumption in sleep mode, it is recommended
to disable the pull-ups by writing the Port register to zero before entering sleep.
The XMEM interface also provides a bus keeper on the AD7:0 lines. The Bus Keeper
can be disabled and enabled in software as described in “Special Function IO Register –
SFIOR” on page 30. When enabled, the Bus Keeper will keep the previous value on the
AD7:0 bus while these lines are tri-stated by the XMEM interface.
External memory devices have various timing requirements. To meet these require-
ments, the ATmega162 XMEM interface provides four different wait-states as shown in
Table 3. It is important to consider the timing specification of the external memory
device before selecting the wait-state. The most important parameters are the access
time for the external memory in conjunction with the set-up requirement of the
ATmega162. The access time for the external memory is defined to be the time from
receiving the chip select/address until the data of this address actually is driven on the
bus. The access time cannot exceed the time from the ALE pulse is asserted low until
data must be stable during a read sequence (t
123 on page 268). The different wait-states are set up in software. As an additional fea-
ture, it is possible to divide the external memory space in two sectors with individual
wait-state settings. This makes it possible to connect two different memory devices with
different timing requirements to the same XMEM interface. For XMEM interface timing
details, please refer to Figure 116 to Figure 119, and Table 116 to Table 123.
Note that the XMEM interface is asynchronous and that the waveforms in the figures
below are related to the internal system clock. The skew between the internal and exter-
nal clock (XTAL1) is not guaranteed (it varies between devices, temperature, and supply
voltage). Consequently, the XMEM interface is not suited for synchronous operation.
Figure 13. External Data Memory Cycles without Wait-state
Note:
System Clock (CLK
DA7:0 (XMBK = 0)
DA7:0 (XMBK = 1)
1. SRWn1 = SRW11 (upper sector) or SRW01 (lower sector), SRWn0 = SRW10 (upper
(SRWn1 = 0 and SRWn0 =0)
sector) or SRW00 (lower sector).
The ALE pulse in period T4 is only present if the next instruction accesses the RAM
(internal or external).
DA7:0
A15:8
CPU
ALE
WR
RD
)
Prev. addr.
Prev. data
Prev. data
T1
Address
Address
(1)
Address
T2
LLRL
XX
+ t
RLRH
Address
T3
Data
Data
Data
- t
DVRH
in Table 116 to Table
T4
2513C–AVR–09/02