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1
Beginners / Re: Digital Oscilloscope Maximum Input Voltage
« Last post by mike_mike on Today at 07:04:16 pm »
Hello, I checked if the probes of the oscilloscope are correctly calibrated.
Please have a look at the attached screenshots and please tell me if the probes are correctly calibrated.

I already made some important ripple, noise and oscillation measurements for a power supply and I need to know if the probes were correctly calibrated.
2
The MCP23008 can do the job, its jut that its a PITA to get it configured correctly.   Unless code space in the MCU is an issue, there's no reason to swap to the PCF8574.

It should be noted that if you are bringing up I2C for the first time, on an unfamiliar MCU, or writing a bit-banged implementation, a PCF8574 is a very useful chip to have for testing, no matter what the final slave device(s) will be, as its just about the dumbest read/write capable slave device out there, so all you have to do is concentrate on the MCU code and the signals on the I2C bus, without having to consider the possible complexities of configuring a slave device.  I recommend ordering a few, and assembling one on a board with an 8 way DIP switch, to ground its I/Os, and an octal buffer driving eight LEDs (with series resistors), . Put a different colour LED on the /INT pin. Fit jumpers for the slave address and socket the PCF8574 so you can swap it for a PCF8574A. 
3
Test Equipment / Re: GPSDO brands?
« Last post by LapTop006 on Today at 07:00:08 pm »
Most of the major ones are fine, although one thing to look out for is newer models have newer GPS cores, which can be needed (week rollover issues just for a start).
4
Exactly. Roll mode has no trigger...
Interestingly, triggered roll mode (as a additional option) is coming into fashion and also Siglent have introduced it at one point. The important difference to the normal triggered acquisition is that it only works at slow timebases (which applies to roll mode in general), where normal mode leaves you with just an activity bar and the message "slow acquisition" until you finally see a graph (which might take several minutes, depending on timebase settings). By contrast, triggered roll mode gives you the joy of watching the trace developing as soon as the trigger fires, but then it also stops once a full screen width has been recorded, just like a standard acquisition would. This works in normal as well as single trigger mode.
Sorry but this isn't roll mode. It is just showing the signal as it is recorded which isn't new. The older Agilent DSO7000A series are already doing this for example.
5
Microcontrollers & FPGAs / Re: STM32 ADC & Reference
« Last post by imo on Today at 06:57:51 pm »
The internal Vref is 1.2V, you may measure it and then use the above calculation. There is an on-chip temperature sensor as well (has to be calibrated).
This is how I did it in past with BleuPill (stm32f103C8) under stm32duino
Code: [Select]
// Reading Vdd and internal Temperature Sensor
// Internal Temperature sensor at ADC16, VREFINT at ADC17
// BluePill and MapleMini (stm32f103C8)

void setup_vdd_tempr_sensor() {
    adc_reg_map *regs = ADC1->regs;
    regs->CR2 |= ADC_CR2_TSEREFE;    // enable VREFINT and Temperature sensor
    // sample rate for VREFINT ADC channel and for Temperature sensor
    regs->SMPR1 |=  (0b111 << 18);  // sample rate temperature
    regs->SMPR1 |=  (0b111 << 21);  // sample rate vrefint
    adc_calibrate(ADC1);
}

void setup(){
    setup_vdd_tempr_sensor();
    Serial.begin(115200);
    delay(1);
}

void loop() {
    float tempr, vdd;
    // reading Vdd by utilising the internal 1.20V VREF
    vdd = 1.20 * 4096.0 / adc_read(ADC1, 17);
    // following 1.43 and 0.0043 parameters come from F103 datasheet - ch. 5.9.13
    // and need to be calibrated for every chip (large fab parameters variance)
    tempr = (1.43 - (vdd / 4096.0 * adc_read(ADC1, 16))) / 0.0043 + 25.0;
    Serial.print("Vdd=  ");
    Serial.print(vdd);
    Serial.println(" V");
    Serial.print("Temp= ");
    Serial.print(tempr);
    Serial.println(" C");
    delay(500);
}

Code: [Select]
Temp= 38.32 C
Vdd=  3.31 V
Temp= 39.91 C
Vdd=  3.32 V
Temp= 39.67 C
Vdd=  3.32 V
Temp= 38.49 C
Vdd=  3.32 V

What could be done is to "calibrate" the internal Vref - do measure its dependency on Vdd and the temperature, and create a "calibration table". Has to be done for each chip individually, however.
6
Repair / Re: Fluke 289 not quite sorted.
« Last post by Samogon on Today at 06:57:40 pm »
OL on open corcuit is ok.
7
Manufacturing & Assembly / Re: Essemtec Fox - thoughts?
« Last post by Kjelt on Today at 06:56:14 pm »
I wrote from stratch some python code to create VIOS files. ( thats what Yamaha / Phillips/ Assemblontec ) use.  ( all same machiens, multiple brands). Its highly custom to my system.     It did take some time.  I'm using YV-100ii's and they are old, but they are workign really well for me.    Am going to add a third one soon.
Do you perhaps have a document with the CAN codes/protocol of an Assembleon Type:  PA 2655 feeder?
I recently purchased 15 pieces for €2,50/kg  :) Now I am trying to find any information to get them up and running.
What I discovered thusfar is they only need 12V and ground and have a two wire CAN interface, it should be running autonomously detecting the pickhead through the disturbance of an IR beam, but I still would like to find out what the CAN protocol does, perhaps it also needs some ready or power on command.
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In general when dealing with RS232 ports you'll need a straight wired (1 to 1) between male / female and a crossed (NULL modem) cable between male / male.

But it's RS232, so good luck.

Picking up a breakout with LEDs can be particularly handy for figuring out the exceptions.

I've taken to carrying DB9->RJ45 adapters intended for data networking, as well as a rollover RJ45->RJ45 (pin1->8, 2->7, etc.) combined with a normal Cisco console cable, and a USB-Serial I trust, with that combo I can talk to the vast majority of kit out there.
9
Why did Jack03 get banned from this forum? I am currently in a transaction with him (awaiting receipt of shipment of Signal Hound BB60C).
Thank you
10
Test Equipment / Re: Test Equipment Anonymous (TEA) group therapy thread
« Last post by med6753 on Today at 06:49:23 pm »
I ordered my DE5000 3 weeks ago.  Got a notice this morning that states:

"Your item has been processed through our facility in ISC NEW YORK NY(USPS) at 5:21 am on October 21, 2018."

I googled about it and all it means is that it arrived, not departed from.   (Government double speak at work?)  God alone knows how long it will linger there. 

Anyone else ever have it take this long to get a package from Japan?

If it came in though JFK customs (most likely) in my experience it will move along quickly.
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