Testing a Frequency Generator Module (#57) - Also, now over 200 subscribers ! 

You got ripped off. Aliexpress its under $2

You'd probably be better to use an Arduino rather than this module. For example, this project: www.electroschematics.com/9540/arduino-fan-speed-controlled-temperature/

the output is switched trough a transistor, which gives quite a large peak-peak signal, but due to the high impedance you normally need to output through an amplifier to hear it.

@@MartynDavies Thank you! I'm seriously considering to give it a try.

No, 1Hz is the lowest this goes. I haven't come across any low-frequency PWM modules.

I have a more recent module here that has slightly different commands - F1000 selects 1kHz, F10000 selects 10kHz. The duty cycle command is more flexible also - you can send 'D2' or 'D98' to select 2% or 98% duty cycle. Try these.

I haven't encountered that, but I haven't driven the module at more than 5V. I would suspect that the regulator is oscillating, although the 8V looks within its capabilities from the datasheet. You could try putting more capacitance around the regulator, or put a zener in series with it to drop some of the voltage.

@@MartynDavies Hi Martyn. I’ll try your suggestions. Do you think the unit is faulty? Thank you for your quick response. Keep up the great work.

@@joedelamo1435 No, not necessarily faulty, but they do try to reduce the bill of materials, e.g. by minimising components and sometimes extra decoupling capacitors can be a help.

I'm not sure what you mean by 'monophase'?

@@MartynDavies Hi Martyn .Thanks for replying. How can I send a snapshot of the waves to you?

It's definitely not designed to be TTL compatible, but will probably work as long as it is run off 5V. Rather than plug it into an expensive piece of equipment, buy a 74xx TTL chip, e.g. 74LS00 and connect the frequency generator to that, make sure that it works and doesn't burn out.

It's the end of the backlight structure, and seems to be where the backlight LED is attached. As far as I can see the backlight is permanently on - it would be nicer if it were controlled by the microcontroller.

thanks.perhaps the power supply could be cut by snipping of the leads to the back light or putting a mini dip switch. i wonder what the power consumption is. the led version used about 18 milliamps at 5volts.

it looks like just one LED in there, so that sounds about right

I'm still working on it, Mark. I have an stm8s003 on an evaluation board, and I just built a code sample yesterday to try to understand the on-board UART, and see if there's something obvious that I'm missing about how to use serial. I can't find any further advice online about how to use the serial port on this frequency generator module (other than the same document that's listed on the icstation site). Interestingly, there is also an earlier similar frequency generator (with 2 channels and a different 7-segment display) , which also seems to have problems with the serial interface. I might get one of these also, and see if I can make any progress with that.

Looks Like These are the commands for this PWM module. Cheers Communication Standard: 9600 bps Data bits: 8 Stop bit: 1 Check digit: none Flow control: none 1>. set the frequency of the PWM "F101": Set the frequency to 101 HZ (001 to 999) "F1.05": set the frequency of 1.05 KHZ (1.00 ~ 9.99) "F10.5": Set the frequency to 10.5KHZ (10.0 ~ 99.9) "F1.0.5": set the frequency of 105KHZ (1.0.0 ~ 1.5.0) 2>. set the PWM duty cycle "DXXX": set the PWM duty cycle to XXX; (001 ~ 100) Such as D050, set the PWM duty cycle is 50% 3>. read the set parameters Send a "read" string to read the set parameters. Set successfully return: DOWN; Setup failed to return: FALL.

Thanks for your comment. I actually have it working now - I'll release a video shortly revealing the secret.

Mark - I've got the answer to the serial comms - see my new video: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-1gkhW2-eBPA.html

I bought mine from icstation.com in China, but I've seen the same item listed on ebay from UK sellers (more expensive, but faster shipping)

I bought this one. www.ebay.co.uk/itm/Signal-Generator-PWM-Pulse-Frequency-Duty-Cycle-Adjustable-Module-LCD-3-3V-30V-H/382432921538?_trkparms=aid%3D333200%26algo%3DCOMP.MBE%26ao%3D1%26asc%3D20171012094517%26meid%3D801272f5de3949a484960ac572a0605e%26pid%3D100008%26rk%3D1%26rkt%3D11%26sd%3D391905048325%26itm%3D382432921538%26pmt%3D1%26noa%3D0%26pg%3D2047675&_trksid=p2047675.c100008.m2219

Actually, it doesn't really have two outputs - you can see from the back of the board that both pins are connected by a track

The documentation only talks about integer steps: 2>. set the PWM duty cycle "DXXX": set the PWM duty cycle to XXX; (001 ~ 100) Such as D050, set the PWM duty cycle is 50%

Thank You

The frequency goes up to 150kHz and actually gives quite a nice square wave at the higher frequencies. According to my oscilloscope, the display reads a little low (1%), so at 100kHz (indicated) my 'scope says 98.9 kHz

Спасибо за информацию) И ещё, а выходное напряжение не меняется оно постоянно?

I don't know much about brushless motors. I think there might be a risk of back EMF from the motor coil damaging the output transistor.

I'm not sure, but it will be defined by that output transistor and its resistor

yes

If you look later in the video, it does have a transistor output stage, so it probably can drive a small motor. With inductive loads like motors and electromagnets it's usually a good idea to have a reverse diode across the coil, otherwise otherwise back EMF from the coil will go through the transistor and may damage it (e.g. see electronics.stackexchange.com/questions/110574/how-to-choose-a-flyback-diode-for-a-relay)

Not that I remember

thanks, I've taken the link off - icstation seem to have a problem at that location currently

The core electronics run off 3.3V, but there is a small voltage regulator on board (you can see it on the upper right at 00:30 in the video when I turn the board over). The specifications say that the max input is 30V, but I personally don't believe that regulator will survive 30V without any kind of heatsink. I'd be reluctant to go over 12V.

@@MartynDavies Thanks for quick Answer

In brief, because you need to send the command in a contiguous block of characters and you must not add CR or LF to the end of the command. I show it working in part 3 ( ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-1gkhW2-eBPA.html )

I doubt if the device will survive 12V

Possibly. This link says its rated to 30v.

I'll look if I have a ht1621-based LCD display somewhere