AT90USB647 Atmel Corporation, AT90USB647 Datasheet - Page 30

• Manufacturer Part Number: AT90USB647
• Manufacturer: Atmel Corporation

Specifications of AT90USB647

• Flash (kbytes): 64 Kbytes
• Pin Count: 64
• Max. Operating Frequency: 16 MHz
• Cpu: 8-bit AVR
• # Of Touch Channels: 16
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 48
• Ext Interrupts: 16
• Usb Transceiver: 1
• Usb Speed: Full Speed
• Usb Interface: Device + OTG
• Spi: 2
• Twi (i2c): 1
• Uart: 1
• Graphic Lcd: No
• Video Decoder: No
• Camera Interface: No
• Adc Channels: 8
• Adc Resolution (bits): 10
• Adc Speed (ksps): 15
• Analog Comparators: 1
• Resistive Touch Screen: No
• Temp. Sensor: No
• Crypto Engine: No
• Sram (kbytes): 4
• Eeprom (bytes): 2048
• Self Program Memory: YES
• Dram Memory: No
• Nand Interface: No
• Picopower: No
• Temp. Range (deg C): -40 to 85
• I/o Supply Class: 2.7 to 5.5
• Operating Voltage (vcc): 2.7 to 5.5
• Fpu: No
• Mpu / Mmu: no / no
• Timers: 4
• Output Compare Channels: 10
• Input Capture Channels: 1
• Pwm Channels: 9
• 32khz Rtc: Yes
• Calibrated Rc Oscillator: Yes

5.5
5.5.1
5.5.2
30
External Memory Interface
AT90USB64/128
Overview
Using the External Memory Interface
With all the features the External Memory Interface provides, it is well suited to operate as an
interface to memory devices such as External SRAM and Flash, and peripherals such as LCD-
display, A/D, and D/A. The main features are:
•
•
•
•
When the eXternal MEMory (XMEM) is enabled, address space outside the internal SRAM
becomes available using the dedicated External Memory pins (see
10-3 on page
Figure 5-4.
The interface consists of:
The control bits for the External Memory Interface are located in two registers, the External
Memory Control Register A – XMCRA, and the External Memory Control Register B – XMCRB.
• AD7:0: Multiplexed low-order address bus and data bus.
• A15:8: High-order address bus (configurable number of bits).
• ALE: Address latch enable.
• RD: Read strobe.
• WR: Write strobe.
Four different wait-state settings (including no wait-state).
Independent wait-state setting for different external Memory sectors (configurable sector size).
The number of bits dedicated to address high byte is selectable.
Bus keepers on data lines to minimize current consumption (optional).
79, and
External Memory with Sector Select
Table 10-9 on page
E xternal M emory
(0-60K x 8)
M emory C onfiguration A
83). The memory configuration is shown in
I nternal memory
L ower sector
U pper sector
SRW01
SRW00
SRW11
SRW10
0 x 0000
ISRAM end
XMem start
0 x FFFF
SRL[2..0]
Figure 2-1 on page
7593K–AVR–11/09
Figure
5,
Table
5-4.