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by PiGraham
Mon Jun 17, 2019 3:02 pm
Forum: General discussion
Topic: Generate multiple PWM signals
Replies: 5
Views: 158

Re: Generate multiple PWM signals

For PWM motor control I would like to have continuous frequency. While pigpio library is really cool (I use it a lot here: https://github.com/Hermann-SW/Raspberry_v1_camera_global_external_shutter ), software PWM frequencies are too restricted: http://abyz.me.uk/rpi/pigpio/pigs.html#PFS I'm curious...
by PiGraham
Fri Jun 14, 2019 1:56 pm
Forum: C/C++
Topic: Camera Image Annotate Position
Replies: 1
Views: 59

Re: Camera Image Annotate Position

How about
MMAL_PARAMETER_CAMERA_ANNOTATE_V4_T

Code: Select all

  uint32_t    justify; //0=centre, 1=left, 2=right

   uint32_t    x_offset; //Offset from the justification edge

   uint32_t    y_offset;

https://github.com/raspberrypi/userland ... s_camera.h
by PiGraham
Fri Jun 07, 2019 7:55 am
Forum: General discussion
Topic: light detector with photo transistor
Replies: 33
Views: 865

Re: light detector with photo transistor

I have tried the cicrcuit with 100K resistor and exposing it to the camera flashlight but it is giving max 400mV. So it is definitely responding to light level then? Yes it is responding to light level but not to that smd led from the chip. How are you positioning the LED and phototransistor? Does ...
by PiGraham
Fri Jun 07, 2019 7:51 am
Forum: General discussion
Topic: How many 2.5" drives?
Replies: 19
Views: 572

Re: How many 2.5" drives?

You should try to test a maximum load condition. Four drives all spinning up at once and moving the heads at the same time could be very different to 3 drives idling and one active. Make sure you don't loose drives at moments of peak power demand. Your best option for power distribution is probably ...
by PiGraham
Thu Jun 06, 2019 1:33 pm
Forum: General discussion
Topic: light detector with photo transistor
Replies: 33
Views: 865

Re: light detector with photo transistor

rajbuddy007 wrote:
Thu Jun 06, 2019 12:43 pm

I have tried the cicrcuit with 100K resistor and exposing it to the camera flashlight but it is giving max 400mV.
So it is definitely responding to light level then?
by PiGraham
Thu Jun 06, 2019 12:11 pm
Forum: General discussion
Topic: light detector with photo transistor
Replies: 33
Views: 865

Re: light detector with photo transistor

Data for the LED shows luminous intensity of 110mcd This calculator shows an illuminance of 27500lx at 2mm using 0.110 candela and 0.002m and 1100lx at 10mm if we just assume an isotropic radiation pattern. So you should have planty of light from the LED to operate the sensor if you aim them right a...
by PiGraham
Thu Jun 06, 2019 11:57 am
Forum: General discussion
Topic: light detector with photo transistor
Replies: 33
Views: 865

Re: light detector with photo transistor

I dont think it will give desired output for the light which i have to detect. Please check the datasheet of the smd led. Should i use comparator for it? SMD LED https://www.mouser.de/datasheet/2/216/APTD1608LSURCK-1102303.pdf Before you do anything else make sure the sensor actually works. You sho...
by PiGraham
Thu Jun 06, 2019 11:08 am
Forum: General discussion
Topic: light detector with photo transistor
Replies: 33
Views: 865

Re: light detector with photo transistor

The spec says Collector light current 200uA at 5V and 200lx illuminance, 70uA at 20 lx so you could expect 200uA in a bright daylit room, maybe <=100uA in the dark room in your photo. https://en.wikipedia.org/wiki/Illuminance#Common_illuminance_levels So connected as pcmanbob's circuit with a 10k pu...
by PiGraham
Wed Jun 05, 2019 8:11 am
Forum: General discussion
Topic: light detector with photo transistor
Replies: 33
Views: 865

Re: light detector with photo transistor

Please help . We have helped. I gave you a link to a tutorial for using an optoisolator with RPi that shows the connections for a phototransistor. Burngate gave you useful suggestions for adapting to your specific use. The code is like code for any digital gpio input like a button or a sensor. Try ...
by PiGraham
Tue Jun 04, 2019 3:18 pm
Forum: Automation, sensing and robotics
Topic: RS-232C Terminal to remotely control receiver volume. Can I do that?
Replies: 5
Views: 134

Re: RS-232C Terminal to remotely control receiver volume. Can I do that?

mikronauts wrote:
Tue Jun 04, 2019 3:03 pm
You could also use an ir led and lirc.

That is a great suggestion if you have a remote controll you can scan to read volume commands because you don't need to find possibly obscure doccumentation.
by PiGraham
Tue Jun 04, 2019 3:15 pm
Forum: Automation, sensing and robotics
Topic: RS-232C Terminal to remotely control receiver volume. Can I do that?
Replies: 5
Views: 134

Re: RS-232C Terminal to remotely control receiver volume. Can I do that?

Hi, guys, I'm wondering if there is a way to remotely control the volume on my stereo receiver using a raspberry pi connected to the receiver's RS-232C terminal. This is mostly a question about your receiever and it's capability to adkjust volume via serial commands. At the very least you would hav...
by PiGraham
Tue Jun 04, 2019 11:04 am
Forum: Automation, sensing and robotics
Topic: Checking when food/water bowls are empty?
Replies: 22
Views: 747

Re: Checking when food/water bowls are empty?

What kind of food will you use? Will it leave the QR clean enough to read reliably, or might food remnants or muddy footprints cause problems? Debris faling into the bowls might also be tricky. The bowls are going to be inside the house, so hopefully debris is not a problem. Was going to use dry bi...
by PiGraham
Tue Jun 04, 2019 10:57 am
Forum: Automation, sensing and robotics
Topic: Checking when food/water bowls are empty?
Replies: 22
Views: 747

Re: Checking when food/water bowls are empty?

What kind of food will you use? Will it leave the QR clean enough to read reliably, or might food remnants or muddy footprints cause problems? Debris faling into the bowls might also be tricky.
by PiGraham
Tue Jun 04, 2019 9:53 am
Forum: General discussion
Topic: light detector with photo transistor
Replies: 33
Views: 865

Re: light detector with photo transistor

Thank for the reply. I want to detect a light from this LED. Please do check and tell me what should be the best practice for it? https://www.mouser.de/datasheet/2/216/APTD1608LSURCK-1102303.pdf Connect it as the phototransitor part of an optoisolator. http://raspberrypihobbyist.blogspot.com/2012/0...
by PiGraham
Tue Jun 04, 2019 8:52 am
Forum: General discussion
Topic: light detector with photo transistor
Replies: 33
Views: 865

Re: light detector with photo transistor

You may not need a comparator if the the light from the LED is enough to turn the phototransistor on enough to pull a GPIO to a safe on or off level against a pullup, and allow the GPIO to return to the opposite state when the LED is off. If youoptically couple the sensor closely to the LED and excl...
by PiGraham
Tue Jun 04, 2019 8:34 am
Forum: Automation, sensing and robotics
Topic: Checking when food/water bowls are empty?
Replies: 22
Views: 747

Re: Checking when food/water bowls are empty?

Whichever method you choose it may not matter if animals climb into bowls. If the objective is to detect EMPTY bowls then the significant reading is when there is nothing in the bowl. Hedgehogs or rats aren't going to be permanently in the bowls and when they leave you get a reading of whatever is l...
by PiGraham
Sun Jun 02, 2019 8:24 am
Forum: Automation, sensing and robotics
Topic: Self-managing race car air suspension
Replies: 7
Views: 358

Re: Self-managing race car air suspension

I want to try and build an "affordable" system that can actively monitor and adjust air pressure in each of the 4 air-shocks using height as the reference measurement. The plan is to use these shocks https://www.airliftperformance.com/product/82607/ and this encoder https://www.adafruit.com/product...
by PiGraham
Tue May 28, 2019 10:38 am
Forum: Other projects
Topic: georeferencing a voltage
Replies: 5
Views: 1026

Re: georeferencing a voltage

think I might get along faster by programming an android app. where to start with that? (a more experienced friend has advised me that phones are difficult to program) You could check out https://appinventor.mit.edu/explore/ for something easy to get into but I don't know of would be any use for wh...
by PiGraham
Mon May 27, 2019 10:40 am
Forum: Camera board
Topic: Stereo Vision on Raspberry Pi 3B+
Replies: 13
Views: 676

Re: Stereo Vision on Raspberry Pi 3B+

This could be relevant. Maybe you could use RPi compatible ArduCam camera modules with external reset to synchronise two sensors. https://www.raspberrypi.org/forums/viewtopic.php?f=43&t=241418&sid=b02a0a0ccb8f55f99392bd24bb50728e Only if you also have the external strobe lighting required, otherwis...
by PiGraham
Mon May 27, 2019 7:52 am
Forum: Camera board
Topic: Stereo Vision on Raspberry Pi 3B+
Replies: 13
Views: 676

Re: Stereo Vision on Raspberry Pi 3B+

This could be relevant.
Maybe you could use RPi compatible ArduCam camera modules with external reset to synchronise two sensors.

viewtopic.php?f=43&t=241418&sid=b02a0a0 ... 24bb50728e
by PiGraham
Sun May 26, 2019 1:41 pm
Forum: Camera board
Topic: Stereo Vision on Raspberry Pi 3B+
Replies: 13
Views: 676

Re: Stereo Vision on Raspberry Pi 3B+

I gave you what I knew. This isn't something I have done.
by PiGraham
Sat May 25, 2019 12:02 pm
Forum: Camera board
Topic: Stereo Vision on Raspberry Pi 3B+
Replies: 13
Views: 676

Re: Stereo Vision on Raspberry Pi 3B+

As I know at the moment, there are two solutions for my current problem. I want to take a pair of images from two pi camera at the same time in order to do stereo vision. 1. The first solution is to use two separate Pi Compute board and 2 separate Pi camera for each board and to use GStreamer. 2. T...
by PiGraham
Fri May 24, 2019 5:49 pm
Forum: Camera board
Topic: Stereo Vision on Raspberry Pi 3B+
Replies: 13
Views: 676

Re: Stereo Vision on Raspberry Pi 3B+

As I know at the moment, there are two solutions for my current problem. I want to take a pair of images from two pi camera at the same time in order to do stereo vision. 1. The first solution is to use two separate Pi Compute board and 2 separate Pi camera for each board and to use GStreamer. 2. T...
by PiGraham
Thu May 23, 2019 3:54 pm
Forum: Automation, sensing and robotics
Topic: need super small PIR sensor
Replies: 16
Views: 706

Re: need super small PIR sensor

For a mirror you may be able to use the PIR without the dome. The dome gives the sensor a wide area coverage but the senor itself is small. You may find it triggers OK without the dome if you move directly in front of it. That's probably OK for a mirror unless you want the system to boot up as soon ...

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