M55800A Atmel Corporation, M55800A Datasheet - Page 84

• Manufacturer Part Number: M55800A
• Manufacturer: Atmel Corporation

Specifications of M55800A

• Flash (kbytes): 0 Kbytes
• Pin Count: 176
• Max. Operating Frequency: 33 MHz
• Cpu: ARM7TDMI
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 58
• Ext Interrupts: 58
• Usb Speed: No
• Usb Interface: No
• Spi: 1
• Uart: 3
• Graphic Lcd: No
• Video Decoder: No
• Camera Interface: No
• Adc Channels: 8
• Adc Resolution (bits): 10
• Adc Speed (ksps): 72
• Resistive Touch Screen: No
• Dac Channels: 1
• Dac Resolution (bits): 10
• Temp. Sensor: No
• Crypto Engine: No
• Sram (kbytes): 8
• Self Program Memory: NO
• External Bus Interface: 1
• Dram Memory: No
• Nand Interface: No
• Picopower: No
• Temp. Range (deg C): -40 to 85
• I/o Supply Class: 3.3/5.0
• Fpu: No
• Mpu / Mmu: no / no
• Timers: 6
• Output Compare Channels: 6
• Input Capture Channels: 6
• 32khz Rtc: Yes
• Calibrated Rc Oscillator: No

Memory Interface
3.5
3-14
Address timing
The ARM7TDMI processor address bus can operate in one of two configurations:
•
•
ARM Limited strongly recommends that pipelined address timing is used in new design
to obtain optimum system performance.
ARM Limited strongly recommends that ALE is tied HIGH and not used in new
designs.
Address depipelined configuration is controlled by the APE or ALE input signal. The
configuration is provided to ease the design of the ARM7TDMI processor in both
SRAM and DRAM-based systems.
APE affects the timing of the address bus A[31:0], plus nRW, MAS[1:0], LOCK,
nOPC, and nTRANS.
In most systems, particularly a DRAM-based system, it is desirable to obtain the
address from ARM7TDMI processor as early as possible. When APE is HIGH then the
ARM7TDMI processor address becomes valid after the rising edge of MCLK before
the memory cycle to which it refers. This timing allows longer periods for address
decoding and the generation of DRAM control signals. Figure 3-8 shows the effect on
the timing when APE is HIGH.
SRAMs and ROMs require that the address is held stable throughout the memory cycle.
In a system containing SRAM and ROM only, APE can be tied permanently LOW,
producing the desired address timing. In this configuration the address becomes valid
after the falling edge of MCLK as shown in Figure 3-9 on page 3-15.
nMREQ
D[31:0]
A[31:0]
MCLK
pipelined
depipelined.
SEQ
APE
Note
Copyright © 1994-2001. All rights reserved.
Figure 3-8 Pipelined addresses
ARM DDI 0029G