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by drgeoff
Thu Feb 27, 2020 4:04 pm
Forum: Automation, sensing and robotics
Topic: 18650 and Raspberry pi 4 connecting.
Replies: 3
Views: 78

Re: 18650 and Raspberry pi 4 connecting.

You can feed %v directly into the expansion header, but take care as this bypasses protection circuitry. So you need to make sure the supply is within range and you get the polarity right. That is false information about protection circuitry. On a RPi4B there is no polyfuse. The 5 volt pin on the G...
by drgeoff
Thu Feb 27, 2020 3:12 pm
Forum: General discussion
Topic: Raspberry Pi 4B 2GB Price Drop - NOW $35
Replies: 14
Views: 666

Re: Raspberry Pi 4B 2GB Price Drop - NOW $35

jamesh wrote:
Thu Feb 27, 2020 12:22 pm
I don't think I've ever run out of memory on a 4GB Pi TBH.
I'm sure that if there is ever an 8Gbyte RPi4B there will be badly written software which doesn't run comfortably in 4 Gbyte.
by drgeoff
Thu Feb 27, 2020 12:40 pm
Forum: Beginners
Topic: Connecting of 12V with PWM regulator to GPIO pins?
Replies: 5
Views: 97

Re: Connecting of 12V with PWM regulator to GPIO pins?

davidcoton wrote:
Thu Feb 27, 2020 11:53 am
The FET converts the 3V3 GPIO signal to 12V for the fan.
That is badly worded.

The 3.3 volt PWM GPIO signal causes the FET to switch on and off the 12 volt supply to the fan.
by drgeoff
Thu Feb 27, 2020 11:21 am
Forum: General discussion
Topic: Raspberry Pi 4B 2GB Price Drop - NOW $35
Replies: 14
Views: 666

Re: Raspberry Pi 4B 2GB NOW $35 price drop !

HermannSW wrote:
Thu Feb 27, 2020 11:04 am
That is really nice!
But among the 9 German Raspberry distributors only one had a reduced price for the 2GB version.
Not 35$, but 38.50€ = 41.02$.
It is $35 plus local taxes.
by drgeoff
Wed Feb 26, 2020 4:29 pm
Forum: Troubleshooting
Topic: Faulty Device ?
Replies: 16
Views: 320

Re: Faulty Device ?

You probably have already done this but if not try the problem RPi4B with one of the PSUs that the other RPi4s do boot with.
by drgeoff
Wed Feb 26, 2020 11:48 am
Forum: Beginners
Topic: Please help me understand the clock pin of Serial RS232 communication
Replies: 27
Views: 405

Re: Please help me understand the clock pin of Serial RS232 communication

Use a USB to "real RS-232" module to connect RPi to the tool. A USB to "TTL-serial", even one that has 3.3 volt levels on the TTL side will not work.

The "real RS-232" module will have a 9 pin D-type connector.
by drgeoff
Tue Feb 25, 2020 8:59 pm
Forum: Troubleshooting
Topic: No green light after taking sd card out
Replies: 7
Views: 170

Re: No green light after taking sd card out

Did you initiate a software shutdown, wait for it to complete and then remove power before taking the card out?
by drgeoff
Tue Feb 25, 2020 8:46 pm
Forum: Beginners
Topic: Please help me understand the clock pin of Serial RS232 communication
Replies: 27
Views: 405

Re: Please help me understand the clock pin of Serial RS232 communication

The diagrams seem to show it being connected between the PC and keyboard No, the diagrams don't show or even imply that. Look again at the "System Connection Method" pictures. The keyboard is plugged into the "Input Tool", which is then plugged into the PC via a Keyboard cable. There are 2 versions...
by drgeoff
Tue Feb 25, 2020 6:50 pm
Forum: Beginners
Topic: Please help me understand the clock pin of Serial RS232 communication
Replies: 27
Views: 405

Re: Please help me understand the clock pin of Serial RS232 communication

rpdom wrote:
Tue Feb 25, 2020 6:48 pm
The diagrams seem to show it being connected between the PC and keyboard
No, the diagrams don't show or even imply that.
by drgeoff
Tue Feb 25, 2020 6:46 pm
Forum: Beginners
Topic: Please help me understand the clock pin of Serial RS232 communication
Replies: 27
Views: 405

Re: Please help me understand the clock pin of Serial RS232 communication

Two possible modes?

One is RS232 with the normal asynchronous transfer. 2400 baud, 1 start, 8 data, 1 stop.

Another is synchronous. Uses the clock and transfers 52 bits. No start and stop bits.

Maybe the latter one is the native mode and the former is only available when using the Input Tool.
by drgeoff
Tue Feb 25, 2020 5:02 pm
Forum: Beginners
Topic: Nothing happens when connecting to TV via HDMI (solved)
Replies: 9
Views: 10193

Re: Nothing happens when connecting to TV via HDMI (solved)

Sometime connecting Pi to TV via HDMI we need to make some changes in config. file but it is hit and trial to assign values. For connecting it to TV just bought HDMI to VGA connect it to TV it will automatically detects pi. Many people find that using an HDMI to VGA converter is more hit and miss t...
by drgeoff
Tue Feb 25, 2020 4:56 pm
Forum: Beginners
Topic: Please help me understand the clock pin of Serial RS232 communication
Replies: 27
Views: 405

Re: Please help me understand the clock pin of Serial RS232 communication

OK so it is RS232 compatible. But not directly to the GPIO header pins on a RPi. (Don't need bit-banging so you can ignore that.)

You are incorrect about 52 bits. It is 13 ASCII characters each encoded in 8 bits.

2400 baud, 1 start bit, 1 stop bit, no parity.
by drgeoff
Tue Feb 25, 2020 4:33 pm
Forum: Beginners
Topic: Please help me understand the clock pin of Serial RS232 communication
Replies: 27
Views: 405

Re: Please help me understand the clock pin of Serial RS232 communication

That dial gauge is NOT using an RS232 interface. It is a custom serial interface. You may need to "bit-bang" it. You'll need more details of the electrical signal timing etc. Things like whether the clock is generated by the gauge or must be supplied to it, which edge of the clock is used etc?
by drgeoff
Tue Feb 25, 2020 4:24 pm
Forum: Advanced users
Topic: 2 pi's communicating serially through an optical fiber link
Replies: 9
Views: 346

Re: 2 pi's communicating serially through an optical fiber link

ragishtin wrote:
Tue Feb 25, 2020 12:22 pm
I need to use serial communication because it's a requirement in the project
Ethernet is a serial communication. :)
by drgeoff
Tue Feb 25, 2020 11:51 am
Forum: General discussion
Topic: Dual input lcd 50 pin connector 1 output lcd 50 pin connector
Replies: 2
Views: 87

Re: Dual input lcd 50 pin connector 1 output lcd 50 pin connector

Without knowing what signals are on the cable it is not possible to suggest an electronic switch.

Despite the suggestion above to use an HDMI switch you have more chance of winning the lottery than succeeding to get one of those to switch between two 50 way cables.
by drgeoff
Mon Feb 24, 2020 5:28 pm
Forum: Beginners
Topic: Having trouble setting up headless Zero W
Replies: 4
Views: 132

Re: Having trouble setting up headless Zero W

But now when I try sudo reboot, I get "Putty Fatal Error: Remote side unexpectedly closed connection" and I am scared to create a new host name and password because it will ask to reboot, and if I get an error during a reboot after I change my password I might get locked out. Is there anything I ca...
by drgeoff
Sun Feb 23, 2020 9:45 pm
Forum: General discussion
Topic: Raspberry pi 4 loose wire in micro SD card slot
Replies: 6
Views: 237

Re: Raspberry pi 4 loose wire in micro SD card slot

DirkS wrote:
Sun Feb 23, 2020 7:58 pm
If you mean the bits of metal you can see through the hole in the bottom left of the slot: I think that's the read-only switch / sensor (not used on the Pi)
There is no "read-only" switch on a micro-SD card.
by drgeoff
Sun Feb 23, 2020 11:38 am
Forum: Troubleshooting
Topic: RPI 4 boots only when power connection is done via USB-C port and not power socket !?
Replies: 2
Views: 173

Re: RPI 4 boots only when power connection is done via USB-C port and not power socket !?

This does sound wierd - especially as many of us have recommended switched mains sockets to avoid having to plug/unplug the USB-c connector. Is the OKDO PSU slow to bring up its output? I can't think of anything else it could be! I have one of those Okdo PSUs (UK plug version) powering a RPi4B 4Gby...
by drgeoff
Sat Feb 22, 2020 11:59 am
Forum: General discussion
Topic: Raspberry PI 4 - USB Boot
Replies: 37
Views: 1610

Re: Raspberry PI 4 - USB Boot

this will go on forever until locked.... ....or until the wait is over.... ;) It's an inevitability of any "it will be done when it's done" position when coupled with no updates on progress. No one can truly know if what was said back then still applies or doesn't, so the only way to find out is to...
by drgeoff
Fri Feb 21, 2020 7:57 pm
Forum: Troubleshooting
Topic: RPI4 wont boot red led blinking
Replies: 10
Views: 192

Re: RPI4 wont boot red led blinking

If with 2 official PSUs (one at a time!), no micro-SD card inserted, nothing in the USB ports and nothing connected to the GPIO header, the red LED is flashing I'd say you now have a hardware fault on the RPi board.
by drgeoff
Fri Feb 21, 2020 7:32 pm
Forum: Troubleshooting
Topic: RPI4 wont boot red led blinking
Replies: 10
Views: 192

Re: RPI4 wont boot red led blinking

Hello Thanks but still same blinking. Flashes are regular and wont become constant, thats really weird I tried with phone charger (5v 2A) it does not blink anymore but no green light at boot and wont read my sd card. The 2 official chargers (5V 3A) give red flashing, its really really strange!! How...
by drgeoff
Fri Feb 21, 2020 7:07 pm
Forum: Beginners
Topic: Trouble getting started
Replies: 7
Views: 239

Re: Trouble getting started

rowan.bradley wrote:
Fri Feb 21, 2020 6:43 pm
6. Click Flash. It should write the image to the card. It apparently gave a verification error, which I ignored for now.
Nuff sed!
by drgeoff
Fri Feb 21, 2020 7:02 pm
Forum: Troubleshooting
Topic: RPI4 wont boot red led blinking
Replies: 10
Views: 192

Re: RPI4 wont boot red led blinking

Try removing/unplugging that fan thing. I suspect it is faulty and overloading your PSUs.

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