What causes the crystal to pause? – I have an ARM M0 processor + MCU connected with a 32.768KHz crystal. The crystal is connected to a load capacitor on each of its leads. The load capacitors are connected in parallel so one of its lead is connected to the crystal and another lead connected to the reference ground. I have made a number of boards and they run normally. However, I made some other boards and found that the device seems paused for several seconds after power on. The observation is after I power on the device, it runs normally for about 20 seconds, and then it pauses for about 30 seconds, and then it runs normally again. Why? Read more
AC current measurement using ACS712 current module and PIC16F877A – I’m working on AC current measurements using current sensor module ACS712 with the PIC16f877a microcontroller. I programmed the ADC for Vref=vcc=5V and 8 analog inputs since I’m using AN0 port for analog input for a current sensor module. My aim is to send the ADC data through the GSM modem. But my problem is that every time I get a message, I see different values from 0.25 to 1.85 when I connect a 40W bulb. Below is my setup for measuring AC current below. Read more
8-bit computer question – Do you know where I can get schematics for an 8-bit motherboard that I can use for my 8-bit CPU? I have the schematics for a CPU but I also need the schematics for a motherboard. I could really use help as I’m banging my head against the wall. Read more
Question about SPI1 write – Why can’t I send a complete file to SPI1_write()? I’m using a MikroC Pro for ARM. When I pass the variable to UART1_Write(), I can read all the file content but when I put on SPI1_Write(), I can only read the top part of the file. Anyone know? Read more
PIC16F877A thermometer problem – I’m reading a thermistor and displaying the results on two, 7-segment displays. I’m facing a problem with reading it. When the temp changes between 1-2 or any number the units display is flickering until it get the right number. My display routine is ok when I test it with any fixed number. When it changes from 01 to 02, for example, the right number flickers until it gets stable. Read more
Doubt on stepper motor ratings – I’m using SY57STH76-2804A stepper motor which the datasheet rates at 3.2v, 2.8A, and coil resistance of 1.13Ω. My questions are:
1) Can I drive this motor with 12v/24V ?
2) When I drive with 12V will the current be =12/1.13=10.6A?
3) What is the impact of coil inductance? What should I take care in designing? Read more
Login to a web page running on Raspberry Pi – I want to make a web page that will display some data and which will run on Raspberry Pi. I would use a wifi module attached on one of Raspberry’s USBs. The user should log in with password on the web page wirelessly and see the data. I will also use a temperature sensor that Raspberry Pi should read. Can this be done? What OS do I install on the computer that will help me? I am thinking of installing Raspbian and write code in Python. Or it is better to install Windows and write the code in C+? Where do I start? Read more
Splitting HEX result into 3 separate values – I need to split a HEX value from an ADC. I’ve searched a lot of confusing tutorials about assembly dividing ways but I’m more confused. Also, what is the ADRESL and ADRESH of the ADC converter? Read more
Problem in receiving data from DS18B20 – I am working on a one-wire, protocol-based temperature sensor (DS18b20) which is powered by an external source. I am resetting DS18b20 and then I am sending skip ROM commands. The datasheet says that if the temperature conversion is in progress, then DS18B20 will send zero or one. But in my case, I am only receiving zero. Read more