IBM EM78M611E manual Reset, Saving Power Mode

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EM78M611E

Universal Serial Bus Series Microcontroller

8.5.2 Device Address and Endpoints

EM78M611E supports one device address and three endpoints, EP0 for control endpoint, EP1 and EP2 for interrupt endpoint. Sending data to USB host in EM78M611E is very easy. Just write data into EP’s FIFO, then set flag, and the UDC will handle the rest. It will then confirm that the USB host has received the correct data from EM78M611E.

8.6 Reset

The EM78M611E provides three types of reset: (1) Power-on Reset, (2) Watchdog Reset, and (3) USB Reset.

8.6.1 Power-on Reset

Power-on Reset occurs when the device is attached to power and a reset signal is initiated. The signal will last until the MCU becomes stable. After a Power-on Reset, the MCU enters into the following predetermined states (see below), and then, it is ready to execute the program.

a. The program counter is cleared.

b. The TCC timer and Watchdog timer are cleared.

c. Special registers and Special Control registers are all set to their initial values.

8.6.2 Watchdog Reset

When the Watchdog timer overflows, it causes the Watchdog to reset. After it resets, the program is executed from the beginning and some registers will be reset. The UDC however, remains unaffected.

8.6.3 USB Reset

When the UDC detects a USB Reset signal on the USB Bus, an MCU interrupt occurs, after which it proceeds to perform the specified process that follows. After a USB device is attached to the USB port, it cannot respond to any bus transactions until it receives a USB Reset signal from the bus.

8.7 Saving Power Mode

The EM78M611E provides two options of power-saving modes for energy conservation, i.e., Power Down mode and Dual clock mode.

8.7.1 Power Down Mode

The EM78M611E enters into Power Down mode by clearing the RUN register (IOCE[4]). During this mode, the oscillator is turned off and the MCU goes to sleep. It will wake up when signal from USB host is resumed, or when a Watchdog reset occurs or when an input port state changes.

If the MCU wakes up when I/O port status changes, the direction of the I/O port should be set at input direction, and then read the state of port. For example:

Product Specification (V1.11) 04.20.2007

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(This specification is subject to change without further notice)

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Contents EM78M611E Trademark Acknowledgments 2.1 Appendix Product Specification V1.1Features General DescriptionUniversal Serial Bus Series Microcontroller Product Specification V1.1 Type Definition ApplicationOriginal With Both VNN Pin AssignmentEM78M611EXBP/BM/DM 20-Pin DIP/SOP/SSOP Pin Description Symbol FunctionALU ACC Data & Control BUS Block DiagramProgram Memory Function DescriptionSpecial Purpose Register Data Memory2.2 R1 Timer / Clock Counter Default Value 0B00000000 2.3 R2 Program Counter & Stack Default Value 0B00000000Operation Registers 2.4 R3 Status Register Default Value0B00011XXX R3 0 Carry/Borrow FlagBit Program Memory Page Address Condition2.5 R4 RAM Select Register Default Value 0B00XXXXXX EP0Busy Stall RF Interrupt Status Register Default Value 0B00000000Accumulator Control RegistersTCC Rate WDT Rate Control Register Default Value 0B00111111PS/2 Operation ModeDualFrq.1 DualFrq.0 Frequency Bit P96 P95 P94 P93 P92 P91 P90PH95 PH93 PU8 PU6 PU5 USB Application FIFOs Extra Control RegisterUSB Device Controller USB ApplicationSaving Power Mode ResetInterrupt Dual Clock ModeFunction Description Pattern Detect Application PDASampling Rate and Debounce Length Control RegisterSR.2 SR.1 SR.0 Sampling Rate DB.2 DB.1 DB.0 Debounce TimeR10 PWM1 Duty Cycle Register Erepwm Control Register Default Value 0B00000001Pulse Width Modulation PWM Duty CycleERA AD Channel Select Register Default Value 0B00011111 Analog-To-Digital Converter ADCClock Hz Period/255 s Channel Port ERB AD LSB Data Register Default Value 0B00000000ERC AD MSB Data Register Default Value 0B00000000 ERD AD Control Register Default Value 0B00000000Command Value Action Execution Time Absolute Maximum Ratings DC Electrical CharacteristicSymbol Min Max Unit Symbol Parameter Condition Min Type Max UnitUSB Interface Application Circuit Address Name Bit Bit1 Default Value Special Register MapOperation Registers Extra Register IOCA3 = Address Name Bit Default ValueBinary Instruction Hex Mnemonic Operation Status Affected Instruction SetThis instruction is not recommended for RE, RF operation Code Option Register Address11 16ms Bits 4~12 User ID Address EM78M611E
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