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by JohnneyBoy
Fri Nov 10, 2017 5:07 pm
Forum: General discussion
Topic: Stretch: will not dhcp ip
Replies: 1
Views: 433

Stretch: will not dhcp ip

Hello, Seem to have a very odd issue with stretch, both lite and desktop. Both fail to get an IP via dhcp! If I put jessie up on the same hardware, no problem, gets IP just Fine. What is interesting the request is getting to the dhcp server and giving a 'binding state abandoned' Background: I have a...
by JohnneyBoy
Mon Feb 08, 2016 3:25 pm
Forum: General discussion
Topic: GPIO Buffer circuit pull down
Replies: 10
Views: 1217

Re: GPIO Buffer circuit pull down

Thanks for that.. I'll pop the scope back on and see what voltage is being presented to the input of the SN7407 The calculations above are to the maximum guaranteed values across temperature and individual device variance. You may see something else in your lab setup, but it's usually best to desig...
by JohnneyBoy
Mon Feb 08, 2016 2:35 pm
Forum: General discussion
Topic: GPIO Buffer circuit pull down
Replies: 10
Views: 1217

Re: GPIO Buffer circuit pull down

joan wrote:This is with nothing connected to the GPIO you are measuring apart from a scope?
Only pins 11,12,13, and GND connected, be it tat 11,12,13 are connected to the inputs of the SN7407. I have checked for shorts between adjacent pins of the chip. I will try again, by removing the SN7407.

John
by JohnneyBoy
Mon Feb 08, 2016 2:31 pm
Forum: General discussion
Topic: GPIO Buffer circuit pull down
Replies: 10
Views: 1217

Re: GPIO Buffer circuit pull down

Your approach is reasonable. If I'm reading the SN7407 data sheet correctly, the maximum input low current is 1.6 mA and the maximum input low voltage is 0.8 V. This would suggest your input pull down resistor should be less than (0.8 V / 1.6 mA) or 500 ohms to guarantee a valid logic low input. Th...
by JohnneyBoy
Mon Feb 08, 2016 2:27 pm
Forum: General discussion
Topic: GPIO Buffer circuit pull down
Replies: 10
Views: 1217

Re: GPIO Buffer circuit pull down

1k seems a bit low. You'll be wasting quite a bit of current. 4k7 or higher would be better. GPIO 0-8 default high, the rest on the expansion header default low. Hello 0-8 high.. odd I'm using pins 11,12,13 (GPIO17, GPIO18, GPIO27) on rev 2, so these should be low, which they are not, checked on a ...
by JohnneyBoy
Mon Feb 08, 2016 1:36 pm
Forum: General discussion
Topic: GPIO Buffer circuit pull down
Replies: 10
Views: 1217

GPIO Buffer circuit pull down

Hello, I have been working on a circuit which uses 3 outputs via a buffer chip (SN7407) and have noticed an interesting problem. I have solved it, but wonder if this is the ideal solution. It seems when the Pi is powered up or powered down the GPIO pins (well most) of them go high impedence inputs, ...
by JohnneyBoy
Sun Dec 29, 2013 2:47 pm
Forum: Automation, sensing and robotics
Topic: Driving multiple servos from the RaspberryPi
Replies: 209
Views: 100480

Re: Driving multiple servos from the RaspberryPi

Hello,

I looked like I needed to update the kernel source .config file with a valid one, the driver now compiles.

Just need to test it....

John
by JohnneyBoy
Sun Dec 29, 2013 12:26 pm
Forum: Automation, sensing and robotics
Topic: Driving multiple servos from the RaspberryPi
Replies: 209
Views: 100480

Re: Driving multiple servos from the RaspberryPi

Hello, I'm trying to compile the driver, however I'm, getting the following error /home/servoblaster/PiBits/ServoBlaster/kernel/servoblaster.c:52:27: fatal error: mach/platform.h: No such file or directory I have the latests kernel source downloaded and compiled. (3.10.25) I suspect the include path...

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