Start-Up And Turning Off Of The System; Real-Time Circuit; Fig. 2.10 Reset Controller; Fig. 2.11 Standby Controller - ELCOM Euro-500 Handy Series Service Manual

Euro-500TX Handy

2.2.3 Start-up and turning off of the system

The two most important states of the system are its start-up and turning off. During the start-up it is neces-
sary to ensure the correct initialisation of the microcontroller and all of the logical circuits. The turning off
conversely requires the saving of all vital data and reliable transfer of the microcontroller and logic circuits
into the safe mode.
The E-500TXN microcontroller connexion is designed so that the E-500TXN is powered from the reserve
NiCd accumulator using the VRAM voltage (current consumption is approx. 500 nA) even when the ECR is
turned off. In order for the system to start up and turn off properly, it is necessary to correctly issue RESET
and STBY (stand-by mode activation) signals. The reset and stand-by controllers handle these signals.
Reset signal controller is a circuit that provides:
• reliable initialisation of the E-500TXN microcontroller during the start-up using the active level of
the RESET signal,
• RESET signal activation during the VCC voltage drop below the circuit threshold level.
The active level of the RESET signal is "log.0". The active signal level duration is 150 ms minimum. The
threshold level is the voltage level that causes the RESET signal to be generated. This level is very impor-
tant for proper functionality of the logical circuits. The V6309/L circuit that is used in this ECR type has the
threshold voltage value equal to 4.5 V. Voltages below 4.5 V cause the V6309/L circuit to reset the CPU.
Stand-by signal controller is a circuit that provides:
• reliable leaving of the E-500TXN microcontroller stand-by mode during the ECR start-up,
• STBY signal activation in order to turn on the E-500TXN stand-by mode if the VCC voltage drops
to the circuit threshold level.
The active level of the STBY signal is "log.0". The V6340/F circuit that is used in this ECR type has the
threshold value equal to 4.5 V. If the voltage drops below 4.5 V the V6340/F activates the microcontroller
stand-by mode.
U10
VCC
3
VCC
RST
2
RST
1
G ND
V6309/L

Fig. 2.10 Reset controller

2.2.4 Real-time circuit

The ECR requires the reliable real-time capability i. e. always to retain and calculate the current date and
time. The V3021 circuit provides these functions.
The V3021 circuit contains:
• reader
• shift register
• voltage regulator
• voltage detector
• communication interface
The communication between V3021
and E-500TXN is provided via the
D0 data line and RD and HWR con-
trol signals. The circuit is activated
using the CS2 signal.
The circuit is powered from the re-
serve NiCd accumulator in order to
ensure its functionality even when
the ECR is turned off. Memory back-
-up voltage has to be at least 2.5
V. The real-time circuit consumes
maximum 500 nA from the reserve
accumulator.
16
Service manual
VCC
4.5
4.25
RST
0 150
1
Q2
32k768
C53 C52
15p 15p

Fig. 2.12 Real-time circuit

U11
VCC
2
VCC
STBY
1
OUT
3
t [ms]
G ND
V6340/F
t [ms]

Fig. 2.11 Standby controller

R72
VRAM
10k
U4
3
CS2
1 XI
CS
5
D0
I/O
6
RD
RD
2
7
HWR
WR
XO
V3021
2
© Elcom, s. r. o.
VCC
4.5
4.25
t [ms]
STBY
t [ms]
0
U [V]
0.4
62
31
0
-0.4
1
U [V]
0.8
0.4
t [ s]
0 31 62
2