speedEC
Full Member level 6
Dear friends,
Circuit consists:
1. SIM900B GSM MODULE (3.2V to 4.8V)
2. PIC16F1938 (1.8V TO 5V)
3. PIR MODULE (available on all online store - 3.6 to 5v)
Power Supply: 3.7v, 1450mAh Li_Ion Battery.
Only single power supply used for the entire circuit. I have PCB that was already designed and connect the PIR Module (purchased separately) from PCB.
BATT -> GSM Module
BATT -> 270R resistor -> PIR Sensor
BATT -> Diode -> PIC MCU
PIR OUTPUT Pin connected to PIC MCU EXT INT Pin.
Problem: When GSM Module sends/receives SMS/Call the current consumption can raise up to 2A suddenly. Due to this peak current, voltage drop up to 300mV will occur. At this time, PIR Module also suffer and output pin of PIR Module go high and ext interrupt occurred falsely. I tried to use 1000uF elec cap at input of PIR MODULE. It works fine (no resetting problem and thus no false ext int occurred) sometimes and sometimes NOT. I have tried to use resistor (270 ohms) between batt and PIR Module (as mentioned above here). Sometime works fine and sometimes NOT. Even when not using 1000uF and Resistor, PIR Module works fine sometimes and sometimes NOT.
HT7133, 30mA, LDO used on PIR Module.
What could be the problem? Any idea pl?
thank you
pmk
Circuit consists:
1. SIM900B GSM MODULE (3.2V to 4.8V)
2. PIC16F1938 (1.8V TO 5V)
3. PIR MODULE (available on all online store - 3.6 to 5v)
Power Supply: 3.7v, 1450mAh Li_Ion Battery.
Only single power supply used for the entire circuit. I have PCB that was already designed and connect the PIR Module (purchased separately) from PCB.
BATT -> GSM Module
BATT -> 270R resistor -> PIR Sensor
BATT -> Diode -> PIC MCU
PIR OUTPUT Pin connected to PIC MCU EXT INT Pin.
Problem: When GSM Module sends/receives SMS/Call the current consumption can raise up to 2A suddenly. Due to this peak current, voltage drop up to 300mV will occur. At this time, PIR Module also suffer and output pin of PIR Module go high and ext interrupt occurred falsely. I tried to use 1000uF elec cap at input of PIR MODULE. It works fine (no resetting problem and thus no false ext int occurred) sometimes and sometimes NOT. I have tried to use resistor (270 ohms) between batt and PIR Module (as mentioned above here). Sometime works fine and sometimes NOT. Even when not using 1000uF and Resistor, PIR Module works fine sometimes and sometimes NOT.
HT7133, 30mA, LDO used on PIR Module.
What could be the problem? Any idea pl?
thank you
pmk