Raspberry Pi Forums

karlkiste

SPI and I2C both require a master device and one or more slave devices. In certain setups, multiple master devices can be possible. As far as I know, the Pi can only act as a master, so a direct connection between two Pis isn't possible, not with SPI anyway. MOSI is always an output, MISO is always ...

karlkiste

Sorry, my fault! It works perfectly, the problem was i was sending chars faster then the frames played. If there is more than one char, the control does not work. #> echo p >/tmp/control would have toggled the pause mode No, it wouldn't. The <cr> char appended by echo would make this a two-char comm...

karlkiste

Hi! using raspbian, I could use a named pipe to control omxplayer. Starting it like this: #> mkfifo /tmp/control #> tail -f /dev/null >/tmp/control #keep the pipe open all the time #> cat /tmp/control | omxplayer videofile.mkv #start the player, using the pipe as stdin Then, e.g. #> echo p >/tmp/con...

karlkiste

sjmurdoch wrote: resample the audio files to 48kHz stereo

Yes, in my first posting I wrote that this solves the problem for ALSA output. However, omxplayer clicks, nevermind what sample rate the audio is. I haven't tried the latest release yet (which needs a new firmware, which might be a good omen)

karlkiste

It's not a pretty solution and you will lose a bit of accuracy, but it is a simple one. I couldn't think of a prettier solution. Just two resistors, that is definetly the way I'd go. If you're calibrating the resistors in software, where's the lost accuracy? The biggest error source is usually the ...

karlkiste

I've successfully transfered 100MByte within 20 minutes at 1MBaud. On the sender: #> stty -F /dev/ttyAMA0 1000000 raw #> tail -f /dev/null >/dev/ttyAMA0 #to keep the device open, avoiding glitches on opening #> pv testfile >/dev/ttyAMA0 #only start after starting the receiving process On the receive...

karlkiste

I do not fully understand either... But if you want to get keyboard input to somewhere else than to a getty (this is the program which writes "login:"), you'd have to modify /etc/inittab and start a different program there. I often use a line like: 1:2345:respawn:/bin/login -f pi >/dev/tty1 2>/dev/t...

karlkiste

The specs suggest a maximum of >3M bytes (not bits) per second. I'd be interested in how much you can reliably achieve. So, I'm wiser now... I do not have to fiddle the uart. It is uart0, the full-featured-one, activated at boot. Do not waste a thought about uart1, the "mini-uart". It could only be...

karlkiste

Hah, simply ;-) I thought it was simple, but I can't find out how to decompress the kernel. As the usual scripts did not work, I had a little script try to gunzip the file after cutting away (n=n+1) bytes from the beginning. So this line worked: dd if=kernel.img skip=1 bs=17836 | gzip -d >kernel_un...

karlkiste

To do what you want: gpio -g mode 14 in # Set TxD to input But do turn off the serial port first (edit /boot/cmdline.txt and /etc/inittab) and also note that the Serial port is initialised to serial mode by the GPU before Linux starts, so some text may still be output on it. Thank you! In fact I ha...

karlkiste

killerbobjr has put up a great essay for you, just pick from there what suits your demands.

My aproach would be different, however: I'd have a go with a simple pushbutton wired to a GPIO, and if everything works as I like, I'd start to think about interfacing the real sensor.

karlkiste

Are there specs for the output drivers? I can't find them anywhere. The pins are rated, I'm sure. And I can't imagine why the output specs shouldn't be made public. Just like maximum source/sink current, hi/low voltage, allowable short-circuit duration, clamping diode currents and things like that. ...

karlkiste

karlkiste wrote:
Simply using an uncompressed kernel image should avoid that message
I'll give that a try, [...]

Hah, simply

I thought it was simple, but I can't find out how to decompress the kernel. Seems to be a bit different than on intel platform

karlkiste

Thanks for all the input :-) The GPU [...] does configure those pins to use the UART alt function, so TX will be configured as an output. Yes, this is OK with me. It's a good feature, and shouldn't be changed. I could live with the outputs connected to each other, if I was sure all the outputs are d...

karlkiste

Who should be in danger? The arduino, if it runs on less than 5V, has to use a 5v-tolerant input. No other harm to fear.

Ground of the two power supplies must be connected, of course, to have a common reference. If they can't be connected, the opto-isolator is required.

karlkiste

Well, the "easiest and cheapest" solution is probably to slaughter a keyboard. It costs five dollars, plugs into the USB connector, and detects over 100 switches in a matrix.

karlkiste

" done, booting the kernel." This string is being sent through the uart at power-up. I've removed all the ttyAMA0 -stuff from cmdline, but this message is still there. I would prefer it to go away. I'm going to connect the TX lines of several Pi's together, and if they output data at boot they would...

karlkiste

[/quote] Another option is the TI Launchpad which is cheaper than most Arduinos but can be programmed with an Arduino like environment.[/quote] Thank you, I'm not into this matter specifically, I use bare PIC controllers. Of course there are other platforms, Arduino is probably the best-known one. D...

karlkiste

I'm using microcontrollers every day, so I'd take one of them. The simplest way to start with microcontrollers is the arduino family of boards. You can connect them via uart, i2c or spi. You would have another device to program, but you can easily read digital and analog inputs, compare values to pr...

karlkiste

You can not send data at that speed. The GPIO pins are no fast enough. We tested the pins and the max frequency is around 100KHz but then you get more of a sinewave out instead of a digital signal. I've just seen a clean rectangle wave out of the TX pin at 4 megabaud, that is 2 MHz when sending "UU...

karlkiste

The CPU has at least two uarts. One of them is a quite simple one which needs relatively much CPU assistance to do transfers, and a more full-featured one which has larger buffers and therefore can use less CPU. Both uarts are wired to the same GPIO pins (GPIO14=TX, GPIO15=RX), and can therefore no...

karlkiste

What you woudn't be able to do is change TXD to be RXD or vice versa (according to my reading of the Broadcom specs). You're certainly right there. Each GPIO pin can serve a limited number of other purposes than "GPIO", but those different purposes are wired in hardware for each pin. Software can s...

karlkiste

Hi! I'd need to change a pin function from a bash script. In detail, I want to switch the uart TX pin to input, so I can connect several Pis in a bus-like manner. The protocol will call one of the Pis, which then will activate its TX line and can talk back to the master. Is there a way to do this, o...

karlkiste

Configured features:
[...]
Raspberry Pi support : no

./configure does not look in the right places by itself. Run it like:

./configure --with-rpi-lib-path="/opt/vc/lib/" --with-rpi-include-path="/opt/vc/include"

the raspbian system is then detected.

karlkiste

I'm interested in how fast you'll be driving the port. So am I :-D I was going to connect pi's (Model A) to each other using short (~10cm / 4") wires, and then rising the speed until I see them glow in broad sunlight ;-) Well, to be realistic, I wouldn't expect to use more than 1Mbaud. And I do not...

Search found 189 matches

Re: SPI between two RPi's

Re: omxplayer does not accept stdin controls

omxplayer does not accept stdin controls

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uart: "Uncompressing Linux..."

Re: Adding 64 plus digital & analog inputs

Re: Adding 64 plus digital & analog inputs

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Re: Is "bash script" a relevant language?

Re: Bash: Is there a utility to change alternate pin functio

Bash: Is there a utility to change alternate pin functions?

Re: Two XBMC (.deb) compiled/prepared for users + instructio

Re: Is "bash script" a relevant language?