EM6517 ETC, EM6517 Datasheet - Page 8

• Manufacturer Part Number: EM6517
• Description: 4 BIT MICROCONTROLLER
• Manufacturer: ETC

Figure 8. Reset Structure
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Figure 8. illustrates the reset structure of the EM6517-1. There are six possible reset sources :
All reset sources activate the System Reset and the Reset CPU . The ‘System Reset Delay’ ensures that the
system reset remains active long enough for all system functions to be reset (active for n system clock cycles).
The ‘CPU Reset Delay’ ensures that the reset CPU remains active until the oscillator is in stable oscillation.
As well as activating the system reset and the reset CPU, the POR also resets all option registers and the sleep
enable (SleepEn) latch. System reset and reset CPU do not reset the option registers nor the SleepEn latch.
Reset state can be shown on Strobe terminal by selecting StrobeOutSel1,0 = 0 in OPTCandStr register.
5.1 Oscillation Detection Circuit
At power on, the voltage regulator starts to follow the supply voltage and triggers the power on reset circuitry,
and thus the system reset. The CPU of the EM6517-1 remains in the reset state for the ‘CPU Reset Delay’, to
allow the oscillator to stabilize after power up.
© EM Microelectronic-Marin SA, 09/99, Rev. A/277
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In te r n a l D a ta B u s
Reset
W rite A c tiv e
R e a d S ta tu s
(1) Internal initial reset from the Power On Reset (POR) circuitry.
(2) External reset from the Reset terminal.
(3) External reset by simultaneous high/low inputs to port A.
(4) Internal reset from the Digital Watchdog.
(5) Internal reset from the Oscillation Detection Circuit.
(6) Internal reset when sleep mode is activated.
W rite R e s e t
R e a d S ta tu s
A n a lo g u e
F ilte r
(Combinations are defined in the registers OptInpRSel1 and OptInpRSel2)
P O R
C k [1 0 ]
S le e p E n
L a tc h
P O R
R e g is te r s & S le e p E n
P O R to O p tio n
O s c illa tio n
W a tc h d o g
D E B O U N C E
D e te c tio n
L a tc h
D ig ita l
FOR ENGINEERING ONLY
C k [1 ]
C k [8 ]
S le e p
L a tc h
O s c illa tio n
W a tc h d o g
D e te c tio n
In h ib it
In h ib it
D ig ita l
P O R
S y s te m R e s e t
C k [1 5 ]
D e la y
E n a b le
A c tiv a te
C P U R e s e t
R e s e t P A D
R e s e t f ro m P o r t A
In p u t C o m b in a tio n
O p tIn p R S le e p
S le e p
D e la y
C k [1 ]
--> POR
--> System Reset, Reset CPU
--> System Reset, Reset CPU
--> System Reset, Reset CPU
--> System Reset, Reset CPU
--> System Reset, Reset CPU
EM6517
R e s e t
C P U