Search found 322 matches

by Cannibal
Wed Feb 03, 2016 6:45 am
Forum: Wireless/RF
Topic: Intermittent Dropouts Observed at 4 feet with XBEE Pro Serie
Replies: 2
Views: 1030

Re: Intermittent Dropouts Observed at 4 feet with XBEE Pro S

Human beings are pretty opaque at 900 MHz, so it could be an issue of blocking the signal, even with a hand - due to the wavelength the spacing between your fingers can look like a solid object. Another issue that can come up is that your hand/body being near the antenna can actually de-tune it away...
by Cannibal
Mon Feb 01, 2016 2:19 pm
Forum: Projects
Topic: Measuring air speed / Prandtl tube
Replies: 4
Views: 595

Re: Measuring air speed / Prandtl tube

Hi there, I haven't done anything like this before, but when using barometers/pressure sensors for altimetry the flow of air over the sensor is a nuisance: Imagine a pressure sensor inside a sealed vessel - it will measure some value of pressure. Now imagine you have put a fan inside that sealed ves...
by Cannibal
Thu Jan 28, 2016 7:13 am
Forum: Projects
Topic: Using Arduino to upgrade 20 year old console's backup memory
Replies: 1
Views: 853

Re: Using Arduino to upgrade 20 year old console's backup me

Looking good! I remember my Aunt had a TurboGrafx-16 growing up, but just the base system none of the add-ons. At the time I thought it was so amazing that the whole game fit on that thin plastic card thing, and that they looked even better than the big chunky plastic boxes that my Nintendo used. In...
by Cannibal
Sun Jan 24, 2016 6:06 pm
Forum: Everything ARM and LPC
Topic: Struggling to understand atomicity of interrupt masking
Replies: 2
Views: 1329

Re: Struggling to understand atomicity of interrupt masking

In this specific case the need is to monitor a pin briefly for edge transitions, where all peripherals for doing input capture/interrupt on change are used by other functions. Since the other peripherals are used up, this leaves polling as the only way to monitor for changes - asm is used to make su...
by Cannibal
Thu Jan 21, 2016 5:16 am
Forum: Wireless/RF
Topic: how many channel are there in ( NRF24L01 )
Replies: 2
Views: 1390

Re: how many channel are there in ( NRF24L01 )

Hi Adel, to my understanding there are a few different meanings of the term 'channel' when we talk about these systems. From the point of view of the RC quadcopter my impression is that a channel is a single control actuator - I think this dates back to the days when RC aircraft were controlled by a...
by Cannibal
Thu Jan 21, 2016 5:09 am
Forum: Projects
Topic: intermittent (?) switch for infrequent, short durations
Replies: 5
Views: 503

Re: intermittent (?) switch for infrequent, short durations

You might be able to make the 555 do it with a long period by adding a counter and an AND gate after, before the motor driver. Set up the 555 to generate a pulse train with a period roughly equal to how long you want the motor to stir for, pass that to an up counter that has its outputs wired to an ...
by Cannibal
Thu Jan 21, 2016 4:56 am
Forum: Projects
Topic: Calculate velocity and position from MPU9150
Replies: 1
Views: 366

Re: Calculate velocity and position from MPU9150

Hi there, This type of sensor is not well suited to navigation - sure it works in principle, but the levels of bias, noise, bias instability, temperature sensitivity, cross axis sensitivity g^2 sensitivity, misalignment etc. are all so bad that they absolutely cannot be used as the only source of po...
by Cannibal
Tue Jan 19, 2016 5:33 am
Forum: Everything ARM and LPC
Topic: Struggling to understand atomicity of interrupt masking
Replies: 2
Views: 1329

Struggling to understand atomicity of interrupt masking

Hi there, While I have been working with embedded systems for long enough, I don't have much experience with ARM and have a situation where I have to write/modify some assembly code. Part of this involves some critical sections and my current method of doing this has just been to rely on the CPSID a...
by Cannibal
Wed Dec 23, 2015 9:02 am
Forum: Projects
Topic: Best IMU for indoor use under $200? How about under $500?
Replies: 1
Views: 386

Re: Best IMU for indoor use under $200? How about under $50

Hi there, With all things inertial, there are serious limitations placed on what the systems can do based on what sort of external information you can feed to them, as well as what periods of time are being considered. For example, if you have an external update which can tell you your heading accur...
by Cannibal
Thu Sep 20, 2012 11:13 am
Forum: SparkFun Product Questions
Topic: Quality USB RS232 - data loss under windows and linux!
Replies: 5
Views: 943

Re: Quality USB RS232 - data loss under windows and linux!

I don't have hardware flow control on the send side, but watching the CTS line on the PC side shows it's not signalling full. Regarding dropping bytes on the send side, it's a very simple buffer scheme, so while it's not foolproof, an off by 1 error would show up very frequently, whereas this error ...
by Cannibal
Wed Sep 19, 2012 3:11 am
Forum: SparkFun Product Questions
Topic: Quality USB RS232 - data loss under windows and linux!
Replies: 5
Views: 943

Quality USB RS232 - data loss under windows and linux!

Hi there, I'm working on a project right now where I have a serial data stream at around 4-6 kB/sec from sensors that are put in a wrapper with a checksum on it inside a micro-controller, then sent over serial to be logged somewhere. Right now I am using a prolific USB to serial cable and find that ...
by Cannibal
Tue Oct 04, 2011 3:04 pm
Forum: SparkFun Site Questions/Comments
Topic: Can't select a shipping method
Replies: 3
Views: 1102

Re: Can't select a shipping method

My order did go through now, and yes I was trying to order one of those nice new scopes.

Thanks for the update (and I see that the number in stock has dropped by 5 in the last hour, so it seems several of us were chomping at the bit).
by Cannibal
Tue Oct 04, 2011 11:23 am
Forum: SparkFun Site Questions/Comments
Topic: Can't select a shipping method
Replies: 3
Views: 1102

Re: Can't select a shipping method

Someone from support got ahold of me and recommended hitting the 'estimate' shipping button in the shopping cart. I'm posting this here since this is apparently a workaround for some, though it isn't working for me :/
by Cannibal
Mon Oct 03, 2011 10:24 pm
Forum: SparkFun Site Questions/Comments
Topic: Can't select a shipping method
Replies: 3
Views: 1102

Can't select a shipping method

Hi there,

When I log into my sparkfun account and select an address the 'Shipping Method' field refreshes but brings up no options...


I've used this address for a dozen or more sparkfun orders over the past 4 years and haven't had this problem before.

Anyone had similar experiences?
by Cannibal
Tue May 03, 2011 8:19 am
Forum: SparkFun Product Questions
Topic: rs232 shifter - dumb question ???
Replies: 1
Views: 357

Re: rs232 shifter - dumb question ???

The only time I used the shifter, I had some issues and decided to just use ds323's and the like in the future. My guess is that the output low voltage of the shifter is too high and reads as a 1 by the processor even when it's supposed to be a zero. You could try resistively loading your RX line to...