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by rzusman
Sat Apr 09, 2016 4:31 pm
Forum: General discussion
Topic: Gigabit Ethernet support in RPI
Replies: 10
Views: 10497

Re: Gigabit Ethernet support in RPI

trlaing wrote:I agree with Matthew. I use one of my Pis as a media server. It is fine when just playing media from it, but painfully slow at copying media to or from it.
Media write times are going to be the bottleneck.
by rzusman
Sat Apr 09, 2016 4:21 pm
Forum: Raspberry Pi OS
Topic: Error messages at boot
Replies: 2
Views: 740

Re: Error messages at boot

Try typing:
dmesg
by rzusman
Fri Apr 08, 2016 6:19 pm
Forum: Troubleshooting
Topic: MOSFET issue
Replies: 4
Views: 888

Re: MOSFET issue

1) Move the resistor to the Drain side.
2) Put an LED w/dropping resistor on the Gate - this will show when the Gate has voltage.
3) Use anti-static protocol. FETs (even big, beefy ones) can be ruined by static, easily.
by rzusman
Thu Apr 07, 2016 6:49 pm
Forum: Compute Module
Topic: Serial port - having my cake, and eating it, too!
Replies: 4
Views: 1175

Re: Serial port - having my cake, and eating it, too!

In case anyone stumbles over this thread: It looks like disabling the boot messages is no issue, since they get echoed to dmesg. As for the getty process - sending a "pause" signal with: # kill -19 $(pgrep -t ttyAMA0) will stop it from using the port until it is resumed with: # kill -18 $(...
by rzusman
Wed Apr 06, 2016 10:54 pm
Forum: Automation, sensing and robotics
Topic: technical question: power source + breadboard
Replies: 6
Views: 1339

Re: technical question: power source + breadboard

I don't see why Option 2 would be a problem, as long as you have enough space.
Do you really need a separate power supply for each group of transistors? Why not just get one big enough to handle the whole thing?
by rzusman
Wed Apr 06, 2016 9:16 pm
Forum: Automation, sensing and robotics
Topic: technical question: power source + breadboard
Replies: 6
Views: 1339

Re: technical question: power source + breadboard

I don't really understand your question about "bread boards." In my world, a "bread board" is a way of prototyping electronic circuits. If you need a particular interface circuit, it can go at the "far" end or the "near" end, but one location will make more se...
by rzusman
Wed Apr 06, 2016 5:52 pm
Forum: Automation, sensing and robotics
Topic: technical question: power source + breadboard
Replies: 6
Views: 1339

Re: technical question: power source + breadboard

A better question is:
"How do you plan on communicating with all these devices?"

Answer that one first.
by rzusman
Tue Apr 05, 2016 2:38 pm
Forum: General discussion
Topic: RS485
Replies: 1
Views: 491

Re: RS485

Your setup should work.

I would measure the ground potential difference between the two ends of your system and see if you are outside of the common-mode range of the MAX485.
by rzusman
Tue Apr 05, 2016 2:04 pm
Forum: Compute Module
Topic: Serial port - having my cake, and eating it, too!
Replies: 4
Views: 1175

Re: Serial port - having my cake, and eating it, too!

Well, this isn't really a Compute Module - specific topic.
It applies to any Pi device.

I want to be able to start and stop getty from my application, so that I can use the serial port for my own purposes, but have a terminal available if I need it.
by rzusman
Mon Apr 04, 2016 4:22 am
Forum: Compute Module
Topic: Serial port - having my cake, and eating it, too!
Replies: 4
Views: 1175

Serial port - having my cake, and eating it, too!

I need to use both serial ports on the Compute Module. I have read about how to prevent the Console from emitting messages to ttyAMA0 by editing cmdline.txt, and how to prevent getty from using it, too. But - those two features are really, really useful, and I would prefer not to lose them. What I w...
by rzusman
Mon Apr 04, 2016 12:20 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Connecting More GPIO
Replies: 13
Views: 2897

Re: Connecting More GPIO

46 pushbuttons only takes 14 I/O to scan.
That leaves 26 for your joystick and everything else.
by rzusman
Sun Apr 03, 2016 6:50 pm
Forum: Troubleshooting
Topic: Mount USB Drive
Replies: 17
Views: 5143

Re: Mount USB Drive

apt-get install usbmount

Works like a charm.
by rzusman
Sun Apr 03, 2016 6:48 pm
Forum: Beginners
Topic: How to save files to USB
Replies: 3
Views: 897

Re: How to save files to USB

Assuming the drive is mounted at /media/usb, do a
cp /path/to/file /media/usb/directory_to_put_it_in

If the drive is mounted somewhere else, you will need to change the path.
by rzusman
Sun Apr 03, 2016 4:42 am
Forum: Windows 10 for IoT
Topic: Deploying your App
Replies: 3
Views: 801

Re: Deploying your App

There are lots of ways to get it onto the Pi.
The easiest might be to copy it to a USB flash drive and plug it into the Pi, then copy it from there.

Or you could transfer it over WiFi or Ethernet using sshfs.
by rzusman
Sat Apr 02, 2016 4:11 pm
Forum: Other projects
Topic: Fully metal heatpipe case?
Replies: 12
Views: 6902

Re: Fully metal heatpipe case?

If you are really that worried about heat, pick up some of those cheap stick-on heat-syncs for the ram and NIC controller, then use the case dankcushions suggested and bolt a NH-D15 CPU cooler on it above the cpu, but if that cooler cost too much you can just use a Hyper 212 (plus or EVO) plenty of...
by rzusman
Sat Apr 02, 2016 4:13 am
Forum: Beginners
Topic: What happens if a USB drive is removed without unmounting?
Replies: 16
Views: 9555

Re: What happens if a USB drive is removed without unmountin

I will, but I've had enough experience with customers to know that they are terrible at following directions...
by rzusman
Sat Apr 02, 2016 2:10 am
Forum: Networking and servers
Topic: Communication without Internet
Replies: 29
Views: 15076

Re: Communication without Internet

Put a TTL-RS232 adapter on it and use the Console.
by rzusman
Sat Apr 02, 2016 2:02 am
Forum: Beginners
Topic: What happens if a USB drive is removed without unmounting?
Replies: 16
Views: 9555

Re: What happens if a USB drive is removed without unmountin

reply to rzusman on unmount scheme As far as my understanding here, Letting device (physical) plug-in and out without (logical) unmount means its logical existence persistently to be used even after plugg-out but if plugged-in again, but that will cause r/w error if an access occurs when currently ...
by rzusman
Fri Apr 01, 2016 11:08 pm
Forum: Beginners
Topic: LED instant on/off?
Replies: 23
Views: 3183

Re: LED instant on/off?

Use an oscilloscope.
by rzusman
Fri Apr 01, 2016 5:18 pm
Forum: Beginners
Topic: What happens if a USB drive is removed without unmounting?
Replies: 16
Views: 9555

Re: What happens if a USB drive is removed without unmountin

Thanks for the suggestion, but the usbmount program seems to do exactly what I need.

The next step is to have the CM run a script (actually, one of two or three scripts) when the USB drive is plugged in.
by rzusman
Fri Apr 01, 2016 12:40 pm
Forum: Beginners
Topic: What happens if a USB drive is removed without unmounting?
Replies: 16
Views: 9555

Re: What happens if a USB drive is removed without unmountin

usbmount (http://usbmount.alioth.debian.org) does exactly what I needed. Mounts a flash drive at the same location (/media/usb) even if it is removed without unmounting. I believe that you might still be confused about what unmount does--- its more than just correctly returning resources to the sys...
by rzusman
Fri Apr 01, 2016 5:17 am
Forum: Beginners
Topic: What happens if a USB drive is removed without unmounting?
Replies: 16
Views: 9555

Re: What happens if a USB drive is removed without unmountin

usbmount (http://usbmount.alioth.debian.org) does exactly what I needed.
Mounts a flash drive at the same location (/media/usb) even if it is removed without unmounting.
by rzusman
Thu Mar 31, 2016 10:58 pm
Forum: Beginners
Topic: What happens if a USB drive is removed without unmounting?
Replies: 16
Views: 9555

Re: What happens if a USB drive is removed without unmountin

OK, so here's what happens: If I have the drive mounted on /mnt/usb, and I unplug it without unmounting it, the next time I plug it in, the device letter gets bumped. In other words, the first time it is /dev/sda1, the next time it is /dev/sdb1, then /sdc1, etc. This is going to be a problem if I ha...
by rzusman
Thu Mar 31, 2016 7:01 pm
Forum: Beginners
Topic: What happens if a USB drive is removed without unmounting?
Replies: 16
Views: 9555

What happens if a USB drive is removed without unmounting?

I'm working on a Compute Module-based system, which will use a USB Flash drive for software updates. Presumably, users will be too stupid and lazy to wait for the system to unmount the drive before they remove it. I'm not concerned about damage to the file system on the USB Flash drive, but I am wor...

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