I am currently making a system using digital camera, my camera resolution is 384x288 4:2:2 YCbCr. My camera works on BT.656 with embedded sync (without hardware sync).
I configured STM32 DCMI with embedded sync and it didn't work. Then I started to debug it and found some weird STM32 DCMI issue:
STM32 DCMI embedded for BT.656 is inverted.
STM32 DCMI document (out of ST's
AN5020):
BT.656 Protocol (from
here):
I have 2 questions:
Has anyone been able to make BT.656 work on STM32H7 or any STF32FXX?
BT.656 resolution for PAL is 720x576 but my camera is 384x288.
What is the format of the camera?
Or: How can I understand how many lines are used?
What I am trying to do is:
Programatically I want to switch on and off the USB power of the RPi B3+ or 4 models.
I know that I can put 0 in /sys/devices/platform/soc/3f980000.usb/buspower but seems like it does not work as expected.
Let me show you what all things I have tried:
Check 1:
Connect USB device (In my case, its camera) to the Rpi
Fire command "lsusb" In the list,
I get my camera listed properly
Check 2:
The camera is connected and lsusb is showing the device
sudo vi /sys/devices/platform/soc/3f980000.usb/buspower and put 0 in it and save the file
again lsusb
All the connected devices list is gone. Looks like its working
BUT:
When I put voltage meeter on the usb port(As showin in screenshot) , it shows same current flowing through the USB ports.
Refer attached screenshot below to understand this issue.
Looking for the solution if anyone knows.
The first flashing went fine, subsequent flashings fail with
Error in initializing ST-LINK device. Reason: No device found on
target.
On an STM32H745 NUCLEO board I have enabled the DEBUG interface and SWO pin by mistake. Is there a way to hard reset this board ?
The "flashing under reset" trick did not work. That is, holding the reset button pressed and immediately releasing it before STM32_Programmer does its thing through ST-Link. A bit of RTFM-ing sometimes helps:
If a deadlock is faced due to a mismatch between the HW
board setting and the FW setting (LDO/SMPS), the user can
recover the board by doing the following:
- Power off the board
- Connect CN11 ‘BT0’ pin (BOOT0) to VDD using a wire
- This changes the BOOT0 pin to 1 instead of 0 and thus the
device boot address is changed to boot address 1 making the
bootloader starting in System memory, instead of starting the
FW in the user Flash (FW that is setting a wrong LDO/SMPS
configuration)
- Power on the board and connect using
STM32CubeProgrammer
- Erase the user Flash
- Power off the board and remove the wire between BOOT0
and VDD
- The board is now recovered and can proceed normally.
Now I got to figure out why it goes deadlocked as soon as I flash my bin... commented some bits of code and rebuilt, sill does it.
LE: found the offending lines:
HAL_PWREx_ConfigSupply(PWR_LDO_SUPPLY);
...
My SystemClock_Config function was all written for LDO power instead of SMPS
If I'm on iOS4, not using a specific handler, and needing the same update interval, what is the difference using the Device motion instead of specific Accelerometer, Gyroscope and Magnetometer updates ?
What happens if one of those 3 features is not available on the device if I use the Device motion ?
I mean, what will return deviceMotionAvailable if one of those feature is not available ?
In iOS 4 the magnetometer is not yet included in device motion API but handled by CLLocationManager (this changed in iOS 5). So if you have a gyro and an accelerometer, deviceMotioAvailable will return true independent of magnetometer. On the other hand if the gyro is missing you will always get false and you need to stay with accelerometerData.
Because Device Motion has one timestamp for both sensors, you will get reliable interpolated values for both sensors. Otherwise Device Motion wouldn't be able to do sensor fusion, the main advantage why this is the preferred way.
You can not rely on a fix frequency for CLLocationManager. didUpdateHeading is called whenever the system 'thinks' it should be. To get the different time coordinates between CLLocationManager and CMDeviceMotion normalised, you can have a look at NSTimeInterval to unix timestamp
Can the iPhone SDK take advantage of the iPhone's proximity sensors? If so, why hasn't anyone taken advantage of them? I could picture a few decent uses.
For example, in a racing game, you could put your finger on the proximity sensor to go instead of taking up screen real-estate with your thumb. Of course though, if this was your only option, then iPod touch users wouldn't be able to use the application.
Does the proximity sensor tell how close you are, or just that something is in front of it?
There is a public API for this. -[UIApplication setProximitySensingEnabled:(BOOL)] will turn the feature on. BTW, it doesn't seem to be using the light sensor, because proximity sensing would tweak out in a dark room.
However, the API call basically blanks the screen when you hold the phone up to your face. Not useful for interaction, sadly.
Assuming you mean the sensor that shuts off the screen when you hold it to your ear, I'm pretty sure that is just an infrared sensor inside the ear speaker. If you start the phone app (you don't have to be making a call) and hold something to cast a shadow over the ear speaker, you can make the display shut off.
When you asked this question it was not accessible via the public API. You can now access the sensor's state via UIDevice's proximityState property. However, it wouldn't be that useful for games, since it is only an on/off thing, not a near/far measure. Plus, it's only available on the iPhone and not the iPod touch.
Evidently the proximity sensor will never turn on if the status bar is in landscape orientation.
i.e, if you call:
[UIApplication sharedApplication].statusBarOrientation = UIInterfaceOrientationLandscapeLeft;
You will no longer get the proximity:ON notifications.
This definitely happens on OS 3.0, I can't test it on a 2.X device since I don't have one with a proximity sensor.
This seems like a bug.
The proximity sensor works via measuring IR reflectance. If you hold the iPhone up to a webcam, you can see a small, pulsing IR LED.
There's a lot of confusion between the proximity sensor and the ambient light sensor. The iPhone has both. The Touch does not have a proximity sensor, making it a poor choice for user input. It would be a bad idea anyway since Apple isn't obligated to locate it in the same place in future devices; you aren't supposed to know or care where it is.
The proximity sensor works by pulsing an infrared LED and measuring the amount of reflectance. You can see this using your iSight camera (most digital cameras are sensitive to IR.) Just launch Photo Booth, initiate a call (or play a voicemail) on the phone and point it at your iSight camera. Note the flashing light next to the earpiece; cover it with your finger and the screen will go black.
The ambient light sensor's API is evidently private at this point.
Just to update, this is possible.
device = [UIDevice currentDevice];
// Turn on proximity monitoring
[device setProximityMonitoringEnabled:YES];
// To determine if proximity monitoring is available, attempt to enable it.
// If the value of the proximityMonitoringEnabled property remains NO, proximity
// monitoring is not available.
// Detect whether device supports proximity monitoring
proxySupported = [device isProximityMonitoringEnabled];
// Register for proximity notifications
[notificationCenter addObserver:self selector:#selector(proximityChanged:) name:UIDeviceProximityStateDidChangeNotification object:device];
As benzado points out, you can use:
// Returns a BOOL, YES if device is proximate
[device proximityState];
There is no public API for this.
In iPhone 3.0 there is official support for the proximity sensor. Have a look at UIDevice proximityMonitoringEnabled in the docs.
If you aren't aiming for the AppStore, you can read my articles here on getting access to those:
Proximity Sensor: http://iphonedevwiki.net/index.php/AppleProxShim
Ambient Light Sensor: http://iphonedevwiki.net/index.php/AppleISL29003
Evidently the proximity sensor will never turn on if the status bar is in landscape orientation.
i.e. if you call:
[UIApplication sharedApplication].statusBarOrientation = UIInterfaceOrientationLandscapeLeft;
You will no longer get proximity:ON notifications.
This definitely happens on OS 3.0, I can't test it on a 2.X device since I don't have one with a proximity sensor.
This seems like a bug.
answered Jul 22 '09 at 5:49
Kevin Lambert
I've encoutered this problem too. It took me a long time to figure out the real reason of why the proximity sensor is not working. When orientation is UIInterfaceOrientationLandscapeLeft or UIInterfaceOrientationLandscapeRight, proximity sensor does not work; while in portrait mode it works well. My iPhone is iPhone 4S (iOS SDK 5.0).
Those proximity sensors are basically a matrix of conductors. The vertical "wires" are tracks on one side of a thin sheet of insulator, the horizontal ones are on the other side. The intersections function as capacitors. Your finger carries an electrostatic charge, so capacitance of each junction varies with proximity. FETs amplify the signal and biasing sets a threshold. In practice the circuit is more complex than that because it has to detect a relative change and reject noise.
But anyway, what the sensor grid tells you is that a field effect has been sensed, and that field effect is characteristic of object about the size of a fingertip and resting on the surface of the display. The centroid of the capacitive disturbance is computed (probably by hardware) and the coordinates are (presumably) reported as numbers on a port most likely brought to the attention of the device OS by an interrupt. In something as sexy as an iPhone there's probably a buffer of the last dozen or so positions so it can work out direction and speed. Probably these are also computed by hardware and presented as numbers on the same port.
#Dipak Patel & #Coderer
You can download working code at
http://spazout.com/google_cheats_independent_iphone_developers_screwed
It has a working implementation of proximityStateChanged a undocumented method in UIApplication.
Hope this helps.
To turn the screen off it's conceivable that more than one sensors is used to figure out if the screen should be turned off or not. The IR proximity sensor described by Cryptognome in conjunction with the Touch screen sensor described by Peter Wone could work out if the iphone is being held close to your face (or something else with a slight electric charge) or if its just very close to something in-animate.