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hydrogeologger / hardware

schematic and wiring instructions
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datalogger V3.1 #2

Open chenmingzhang opened 3 years ago

chenmingzhang commented 3 years ago

TO 210224, cold start, I2C has 5V on the vin. D7 is 0V.

after running power_switch,7,power_switch_status,1, D7 is 5V.

the vin of the 9548 is not

chenmingzhang commented 3 years ago

when D13, which is an reversed switch, is at low status, the Voltage there is 0.25V. the pull up resistor is 4.7K . which means that the pull down resistor of the arduino

we also tried to measure the digital output of the power pins.

power_switch,13,power_switch_status,255 4.81V when it is at high state power_switch,13,power_switch_status,0 0.025V when it is at low state.

perhaps that is because the loop through R15,R13, and Q6.

chenmingzhang commented 3 years ago

also confirmed that a PI zero camera is able to be powered on and take photos, when the camera is connected to switch 8.

chenmingzhang commented 3 years ago

Camera setup trial

For the V3.1 logger, where the digital output can reach up to 5V, the switch between 22 to 49 (using IC) still can not power a PI camera.

The voltage is fluctuating between 3.9 to 4.5V. the current is changing between. 60mA to 140mA.

it is POSIBBLE that we enlarge the capacitor of the power rail to make it working. but the best way is to change the IC.

we have tried to put a current meter at the 5V rail, during booting of a PI zero camera.

The current during booting is ranging between 170mA at busing time, and110mA at idle condition. given a stable 5V input.

chenmingzhang commented 3 years ago

it is very uncomfortable that 5V rail is next to 3.3V and 12V, which give user a chance to connect 5V sensor to 12 rail. one of the solutions could be putting the power pins separated by GNDs.

chenmingzhang commented 3 years ago

C28 is not required as it slows down the desippation of voltage when multiplexer is rebooting