EM6620WS27 datasheet(6/56 Pages) EMMICRO

6 / 56 page

EM6620

www.emmicroelectronic.com

2. Operating modes

The EM6620 has two low power dissipation modes, standby and sleep. Figure 4 is a transition diagram for

these modes.

2.1 ACTIVE Mode

The active mode is the actual CPU running mode. Instructions are read from the internal ROM and executed by

the CPU. Leaving the active mode: via the halt instruction to go into standby mode, writing the SLEEP bit to go

into Sleep mode or detecting the reset condition from port A to go into reset mode.

2.2 STANDBY Mode

Executing a HALT instruction puts the EM6620 into

standby mode. The voltage regulator, oscillator,

watchdog

timer,

LCD,

interrupts,

timers

and

counters are operating. However, the CPU stops

since the clock related to instruction execution

stops. Registers, RAM and I/O pins retain their

states prior to STANDBY mode. STANDBY is

canceled by a RESET or an Interrupt request if

enabled.

2.3 SLEEP Mode

Writing to the Sleep bit in the RegSysCntl1 register

puts the EM6620 in sleep mode. The oscillator stops

and most functions of the EM6620 are inactive. To

be able to write to the Sleep bit, the SleepEn bit in

RegSysCntl2 must first be set to "1". In SLEEP

mode only the voltage regulator is

active to

maintain the RAM data integrity, all other functions

are in reset state. SLEEP mode may be canceled only by the input reset combination from port A

Due to the cold-start characteristics of the oscillator, waking up from sleep mode may take some time to

guarantee stable oscillation. During sleep mode and the following start up the EM6620 is in reset state. Waking

up from sleep mode clears the Sleep flag but not the SleepEn bit. Inspecting the SleepEn allows to determine

if the EM6620 was powered up (SleepEn = "0") or woken from sleep mode (SleepEn = "1").

TAKE CARE !!! To quit sleep mode, one must be sure to have a suitable defined combination of port A inputs

for reset (see section 4.2). The Bit NoInpReset has no action during sleep mode.

Table 2.3.1 Shows the state of the EM6620 functions in STANDBY and SLEEP modes

FUNCTION

STANDBY

SLEEP

Oscillator

Active

Stopped

Oscillator supervisor

Active

Stopped

Instruction execution

Stopped

Interrupt functions

Active

Stopped

Registers and flags

Retained

Reset

RAM data

Retained

Option registers

Retained

Timer/Counter's

Active

Reset

Logic watchdog

Active

Reset

I/O port B

Active

High Impedance, no pulls

Input port A

Active

NoInputRes = "0" for reset generation

Only active for Reset generation

NoInputRes = "X"

LCD

Active

Stopped (display off)

Voltage Level Detector

finishes on going measure, then stop

Stopped

Figure 4 Mode transition diagram

Active

Halt

instruction

Sleep bit

write

IRQ

Standby

Sleep

Reset=1

Reset=0

Reset=1

Reset

EM6620WS27 Datasheet(PDF) 6 Page - EM Microelectronic - MARIN SA

EM6620WS27 Datasheet(HTML) 6 Page - EM Microelectronic - MARIN SA

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56

Datasheet Descarga

Enlace URL