M40800 Atmel Corporation, M40800 Datasheet - Page 60

• Manufacturer Part Number: M40800
• Manufacturer: Atmel Corporation

Specifications of M40800

• Flash (kbytes): 0 Kbytes
• Pin Count: 100
• Max. Operating Frequency: 40 MHz
• Cpu: ARM7TDMI
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 32
• Ext Interrupts: 32
• Usb Speed: No
• Usb Interface: No
• 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: 1.8/3.3
• Fpu: No
• Mpu / Mmu: no / no
• Timers: 3
• Output Compare Channels: 3
• Input Capture Channels: 3
• 32khz Rtc: No
• Calibrated Rc Oscillator: No

Programmer’s Model
2.7.2
2-14
Control bits
All instructions can execute conditionally in ARM state. In Thumb state, only the
Branch instruction can be executed conditionally. For more information about
conditional execution, refer to the ARM Architecture Reference Manual.
The bottom eight bits of a PSR are known collectively as the control bits. They are the:
•
•
•
The control bits change when an exception occurs. When the processor is operating in
a privileged mode, software can manipulate these bits.
Interrupt disable bits
The I and F bits are the interrupt disable bits:
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•
T bit
The T bit reflects the operating state:
•
•
The operating state is reflected on the external signal TBIT.
Never use an MSR instruction to force a change to the state of the T bit in the CPSR. If
you do this, the processor enters an unpredictable state.
interrupt disable bits
T bit
mode bits.
when the I bit is set, IRQ interrupts are disabled
when the F bit is set, FIQ interrupts are disabled.
when the T bit is set, the processor is executing in Thumb state
when the T bit is clear, the processor executing in ARM state.
Caution
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ARM DDI 0029G