SAM7L128 Atmel Corporation, SAM7L128 Datasheet - Page 88

• Manufacturer Part Number: SAM7L128
• Manufacturer: Atmel Corporation

Specifications of SAM7L128

• Flash (kbytes): 128 Kbytes
• Pin Count: 144
• Max. Operating Frequency: 36 MHz
• Cpu: ARM7TDMI
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 80
• Ext Interrupts: 80
• Usb Speed: No
• Usb Interface: No
• Spi: 1
• Twi (i2c): 1
• Uart: 3
• Segment Lcd: 40
• Graphic Lcd: No
• Video Decoder: No
• Camera Interface: No
• Adc Channels: 4
• Adc Resolution (bits): 10
• Adc Speed (ksps): 460
• Resistive Touch Screen: No
• Temp. Sensor: No
• Crypto Engine: No
• Sram (kbytes): 6
• Self Program Memory: YES
• Dram Memory: No
• Nand Interface: No
• Picopower: No
• Temp. Range (deg C): -40 to 85
• I/o Supply Class: 1.8/3.3
• Operating Voltage (vcc): 1.8 to 3.6
• Fpu: No
• Mpu / Mmu: no / no
• Timers: 3
• Output Compare Channels: 3
• Input Capture Channels: 3
• Pwm Channels: 4
• 32khz Rtc: Yes
• Calibrated Rc Oscillator: No

Memory Interface
3-18
Unidirectional data bus
When BUSEN is HIGH, all instructions and input data are presented on the input data
bus, DIN[31:0]. The timing of this data is similar to that of the bidirectional bus when
in input mode. Data must be set up and held to the falling edge of MCLK. For the exact
timing requirements refer to Chapter 7 AC and DC Parameters.
In this configuration, all output data is presented on DOUT[31:0]. The value on this bus
only changes when the processor performs a store cycle. Again, the timing of the data
is similar to that of the bidirectional data bus. The value on DOUT[31:0] changes after
the falling edge of MCLK.
The bus timing of a read-write-read cycle combination is shown in Figure 3-13.
When the unidirectional data buses are being used, and BUSEN is HIGH, the
bidirectional bus, D[31:0], must be left unconnected.
The unidirectional buses are typically used internally in ASIC embedded applications.
Externally, most systems still require a bidirectional data bus to interface to external
memory. Figure 3-14 on page 3-19 shows how you can join the unidirectional buses up
at the pads of an ASIC to connect to an external bidirectional bus.
Copyright © 1994-2001. All rights reserved.
DOUT[31:0]
DIN[31:0]
D[31:0]
MCLK
read cycle
D[31:0]
MCLK
D1
D1
Figure 3-13 Unidirectional bus timing
write cycle
Figure 3-12 Bidirectional bus timing
read cycle write cycle read cycle
Dout
read cycle
Dout
ARM DDI 0029G
D2
D2