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by Gert van Loo
Thu Apr 13, 2017 6:44 am
Forum: Beginners
Topic: to detect when my CNC lathes chuck stopped turning
Replies: 8
Views: 1048

Re: to detect when my CNC lathes chuck stopped turning

There are several ways: 1/ Magnetic You put a small magnet on the chuck and then use a magnetic sensor. The most primitive sensors are magnetic switches, but they may now work well if your chuck is spinning rapidly. Better is a Hall sensor. They come in a tiny packages. 2/ Optical This can be done i...
by Gert van Loo
Wed Apr 12, 2017 9:52 pm
Forum: HATs and other add-ons
Topic: Gertbot and potentiometer feedback
Replies: 7
Views: 3804

Re: Gertbot and potentiometer feedback

Major correction!!! I have been reading this as "gertboard" and potentiometer feedback. Only now do I see it is gertbot and potentiometer feedback. To use a potentiometer and gertbot do the following: You set up one of the gertbot pins in ADC mode and then read the value back. Most people seem to u...
by Gert van Loo
Wed Apr 12, 2017 2:14 pm
Forum: HATs and other add-ons
Topic: Gertbot and potentiometer feedback
Replies: 7
Views: 3804

Re: Gertbot and potentiometer feedback

The raspberry pi pins have to be assigned to be in "SPI-mode". That is: they are controlled by the SPI interface in the PI. Then on the gertboard you have to connect them, using the wires, to the SPI interface of the AD-chip. Next the SPI block inside the Pi needs to be instructed using C or python...
by Gert van Loo
Wed Apr 12, 2017 1:48 pm
Forum: HATs and other add-ons
Topic: Gertbot and potentiometer feedback
Replies: 7
Views: 3804

Re: Gertbot and potentiometer feedback

Celestial_Mech wrote:Excellent, is this where the pins need to be reassigned for the Gertbot, or do some communicate directly to the RPi?
Sorry, I don't understand the question.
by Gert van Loo
Tue Apr 11, 2017 10:24 pm
Forum: Other projects
Topic: ADC and Force Sensor/Accelerometer
Replies: 7
Views: 1747

Re: ADC and Force Sensor/Accelerometer

Well... I don't know about the first part as I know nothing of piezo accelerometers (yes, that is the way you spell "piezo" :roll: ). You might be able to do without the amplifier as the ADC converter has a build-in amplifier. Check the amplitude of your signals against what the data sheet of the AD...
by Gert van Loo
Sun Apr 09, 2017 6:39 am
Forum: Other projects
Topic: ADC and Force Sensor/Accelerometer
Replies: 7
Views: 1747

Re: ADC and Force Sensor/Accelerometer

Sorry, my scathing remark was for the developers of the ADC board, not for you. Also, Most of our wire will be shielded, will that suffice for noise? It will help some. The biggest problems with precision ADC is to keep the digital noise away from the sensitive analog circuit. Good ADC converts ther...
by Gert van Loo
Sat Apr 08, 2017 2:05 pm
Forum: Other projects
Topic: ADC and Force Sensor/Accelerometer
Replies: 7
Views: 1747

Re: ADC and Force Sensor/Accelerometer

Just my two cents worth: In using ADC there are two parameters: number of bits and sampling frequency. Together they determine the data rate which has to be processed and thus if a Pi-Zero can do it. You specified 16 bits for the first but do not mention anything about the second. As to your 16-bits...
by Gert van Loo
Fri Apr 07, 2017 3:01 pm
Forum: HATs and other add-ons
Topic: stepper hat
Replies: 14
Views: 6937

Re: stepper hat

Is this getting off-topic? Maybe. I was not even trying to sell something. I was trying to point out the difference a dedicated ARM core (in this case a Cortex-M3) makes to do real-time tasks. My stepper function is a timer driven interrupt routine running at up to 5KHz. In the routine I not only h...
by Gert van Loo
Thu Apr 06, 2017 4:24 pm
Forum: HATs and other add-ons
Topic: stepper hat
Replies: 14
Views: 6937

Re: stepper hat

Gertbot can do stepping up to 5000 steps/sec with jitter less then 1% :D
by Gert van Loo
Thu Apr 06, 2017 3:52 pm
Forum: HATs and other add-ons
Topic: Gertbot
Replies: 146
Views: 50262

Re: Gertbot

I think you are looking at the wrong section of the GUI. The latest SW versions of the gertbot (from 2.5 upwards) supports quadrature encoders natively. If you have connected the quadrature encoder as per the manual you can interface with it using the Gertbot GUI. In the GUI switch the motor to DC/b...
by Gert van Loo
Tue Apr 04, 2017 6:48 am
Forum: Beginners
Topic: Number of controllable SPI devices possible
Replies: 6
Views: 1191

Re: Number of controllable SPI devices possible

The SPI drivers on the Raspberry-Pi can use almost ANY GPIO pin for chip select. Thus you can have many, many devices connected.
I have read that in a post somewhere, but can't immediately find it anymore. so have a good search in the forum.
by Gert van Loo
Tue Apr 04, 2017 6:45 am
Forum: Troubleshooting
Topic: UART acting strange
Replies: 1
Views: 297

Re: UART acting strange

It should never work with a laptop and your Pi, so I expect there is something you are not telling us. Serial communication with PCs and laptops should have an inverted signal with a voltage between -5V/+5V and -12V/+12V. (That is really plus and minus voltage not 'about' ) This is done using a RS23...
by Gert van Loo
Mon Apr 03, 2017 1:22 pm
Forum: HATs and other add-ons
Topic: Gertbot
Replies: 146
Views: 50262

Re: Gertbot

First use nano to open /boot/cmdline.txt and edit it to disable boot info being sent to the port. sudo nano /boot/cmdline.txt The Pi3 cmdline.txt should look like this: dwc.otg.lpm_enable=0 console=serial0,115200 console=ttyl root=/dev/mmcblk0p7 rootfstype=ext4 elevator=deadline fsck.repair=yes root...
by Gert van Loo
Sun Apr 02, 2017 8:27 pm
Forum: Advanced users
Topic: Incandescent Matrix
Replies: 1
Views: 314

Re: Incandescent Matrix

Hummm, I always like a challenge. So lets do a back-of-an-envelope design. You want 8x64 = 512 lights in a matrix. To do this in a matrix you need minimum SQRT(512) = 23x23 pins. But the Pi has not got 46 I/Os. So then most people start looking for I/O expanders. WRONG!! You don't need 46 I/Os. You ...
by Gert van Loo
Sun Apr 02, 2017 7:23 pm
Forum: Automation, sensing and robotics
Topic: disconnect the power supply to the robot with raspberry pi 3
Replies: 4
Views: 676

Re: disconnect the power supply to the robot with raspberry

You should always shut down. If not you risk that your SD-card becomes corrupted beyond repair. It may go right a few times (or many times) but ultimately it will go wrong. Of course you might take the risk and always have a back-up of the SD-card image. For a clean shut down look for "one button st...
by Gert van Loo
Fri Mar 31, 2017 2:17 pm
Forum: HATs and other add-ons
Topic: Gertbot
Replies: 146
Views: 50262

Re: Gertbot

Excuses for the manual entry about git hub. There is NO gertbot software on GIT. That is something I was planning to do but never got around to it. (That is where the "git:://github.com/< TODO >" text comes from.). The Gertbot hardware and software where out BEFORE the Pi-3. In the Pi-3 some idiot (...
by Gert van Loo
Fri Mar 31, 2017 6:53 am
Forum: HATs and other add-ons
Topic: Gertbot and potentiometer feedback
Replies: 7
Views: 3804

Re: Gertbot and potentiometer feedback

The answer is a simple: yes.
You need to connect the analogue signal to the A/D converter input.
Then use the Raspberry-Pi SPI interface to read from it.

(Sorry for the late reply. I just realised my notifications where going to an old email address)
by Gert van Loo
Mon Mar 27, 2017 10:32 am
Forum: Bare metal, Assembly language
Topic: RPI3 timers in debug state
Replies: 6
Views: 1559

Re: RPI3 timers in debug state

The chapter in the reference manual starts with stating: "This chapter describes the implementation of the ARM Generic Timer as an extension to an ARMv8 implementation. " (The emphasis is mine. ) I am pretty sure that it has not been added to the ARM core in the Pi3. I assume they duplicated the 64-...
by Gert van Loo
Sun Mar 26, 2017 9:15 pm
Forum: Bare metal, Assembly language
Topic: RPI3 timers in debug state
Replies: 6
Views: 1559

Re: RPI3 timers in debug state

Per the ARM spec there should be a block of memory mapped Generic Timer registers that includes a CNTR register. I was surprised by your remark above because I have never seen memory mapped registers in any ARM processor. I found the ARM A53 technical reference manual and DDI0500E_cortex_a53_r0p3_t...
by Gert van Loo
Sun Mar 26, 2017 8:34 pm
Forum: Beginners
Topic: Best expander for high current consumtions
Replies: 5
Views: 963

Re: Best expander for high current consumtions

Just some more indicators: As I said I don't know the value of the pull-ups on the relay board but... Nowadays a LED/opto-coupler needs only 1-2mA thus those expander boards should be fine. (Gone are the old days where you needed 10mA to active an LED.) but as soon as I activate the 10th relay its s...
by Gert van Loo
Sat Mar 25, 2017 10:48 pm
Forum: Beginners
Topic: Best expander for high current consumtions
Replies: 5
Views: 963

Re: Best expander for high current consumtions

each relay need 15-20mA The wording in the link is rather confusing. What needs 15-20mA? The whole boards or each relay or each input? So you must look at the schematics and know how to read them. Maybe not your strongest point. Let me help you: Luckily I have studied that board before. Safety firs...
by Gert van Loo
Sat Mar 25, 2017 10:18 pm
Forum: Troubleshooting
Topic: Motor starts running before running the program
Replies: 3
Views: 556

Re: Motor starts running before running the program

If the motor starts running before you have run the program I doubt it has anything to do with your code. 99% chance that you have a GPIO pin which, after the reset, has the "wrong" level or you have made a wrong connection somewhere. Check all your pins, look what they are after a reset and maybe y...
by Gert van Loo
Fri Mar 24, 2017 6:37 pm
Forum: Bare metal, Assembly language
Topic: RPI3 timers in debug state
Replies: 6
Views: 1559

Re: RPI3 timers in debug state

BCM2835 ARM Peripherals manual states that this counter is "stopped whenever the processor is stopped in debug mode". The PI3 is NOT a BCM2835. In the BCM2835 the timer is outside the ARM. Thus it is not part of, nor controlled by the ARM. In fact I wrote the timer code and added special logic in t...
by Gert van Loo
Tue Mar 21, 2017 4:27 pm
Forum: Beginners
Topic: Is it possible to make a Fitness Pull-up Counter ?
Replies: 3
Views: 622

Re: Is it possible to make a Fitness Pull-up Counter ?

The sensor in the video is an ultra sonic distance sensor, type is an HC-SR04. If you search the Pi forum for 'SR04' you will find that it has been connected to the Pi by various people. This seems a good link: https://github.com/fivdi/pigpio#measure-distance-with-a-hc-sr04-ultrasonic-sensor to star...
by Gert van Loo
Sun Mar 19, 2017 6:33 pm
Forum: Automation, sensing and robotics
Topic: Gertbot missed steps
Replies: 1
Views: 369

Re: Gertbot missed steps

Benny,
sorry never saw your post until today.
Tip: put questions about the gertbot in the gertboard classic section. I am subscribed to that.

What is your current status on this?

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