M42800A Atmel Corporation, M42800A Datasheet - Page 49

• 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

2.2
2.2.1
ARM DDI 0029G
Processor operating states
Switching state
The ARM7TDMI processor has two operating states:
ARM
Thumb
In Thumb state, the Program Counter (PC) uses bit 1 to select between alternate
halfwords.
Transition between ARM and Thumb states does not affect the processor mode or the
register contents.
The operating state of the ARM7TDMI core can be switched between ARM state and
Thumb state using the BX instruction. This is described in the ARM Architecture
Reference Manual.
All exception handling is entered in ARM state. If an exception occurs in Thumb state,
the processor reverts to ARM state. The transition back to Thumb state occurs
automatically on return. An exception handler can change to Thumb state but it must
return to ARM state to allow the exception handler to terminate correctly.
Note
Copyright © 1994-2001. All rights reserved.
32-bit, word-aligned ARM instructions are executed in this state.
16-bit, halfword-aligned Thumb instructions are executed in this state.
Programmer’s Model
2-3