M42800A Atmel Corporation, M42800A Datasheet - Page 53

• Manufacturer Part Number: M42800A
• Manufacturer: Atmel Corporation

Specifications of M42800A

• Flash (kbytes): 0 Kbytes
• Pin Count: 144
• Max. Operating Frequency: 33 MHz
• Cpu: ARM7TDMI
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 54
• Ext Interrupts: 54
• Usb Speed: No
• Usb Interface: No
• Spi: 2
• Uart: 2
• Graphic Lcd: No
• Video Decoder: No
• Camera Interface: No
• Resistive Touch Screen: No
• 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

2.5
ARM DDI 0029G
Operating modes
The ARM7TDMI processor has seven modes of operation:
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•
•
•
•
•
•
Modes other than User mode are collectively known as privileged modes. Privileged
modes are used to service interrupts or exceptions, or to access protected resources.
Each register has a mode identifier as listed in Table 2-1.
User mode is the usual ARM program execution state, and is used for executing
most application programs.
Fast Interrupt (FIQ) mode supports a data transfer or channel process.
Interrupt (IRQ) mode is used for general-purpose interrupt handling.
Supervisor mode is a protected mode for the operating system.
Abort mode is entered after a data or instruction Prefetch Abort.
System mode is a privileged user mode for the operating system.
You can only enter System mode from another privileged mode by modifying the
mode bit of the Current Program Status Register (CPSR).
Undefined mode is entered when an undefined instruction is executed.
Copyright © 1994-2001. All rights reserved.
Note
Table 2-1 Register mode identifiers
Mode
User
Fast interrupt
Interrupt
Supervisor
Abort
System
Undefined
Programmer’s Model
Mode identifier
usr
fiq
irq
svc
abt
sys
und
2-7