Question about coding 7-segment, 5-digit driver – I am planning to use 25Hz-50Hz clock signal to feed the CD4017 decade counter which is used for selecting the digits. In the timer interrupt vector, should I update the data on the each digit? Or, how I can do this? When a button is pressed and an interrupt is created, should it be updated in the interrupt vector by writing value in an array? Read more

74HC595 problem – Can anyone help me verify this circuit?  Read more

C3 USB transmit error – I am simulating a scenario to interface a PIC18F4550 with USB by C# but when I transmit a string from my laptop to the PIC the received data include some 0xFF byte. I download a USB display link library (.dll) but now I cannot fix it. Can anyone help me? Read more

Design of a PIC 12F683-based temperature controlled DC fan –  I am attempting to build a temperature controlled DC fan based on a PIC12F683 microcontroller. Currently my circuit is not working and I need some help to find the problem. So far this is what I have. Read more 

How does int main work in C? – Can anyone explain how does int main work in C language? There are two flags we can set or reset. What is happening in the program? Read more

ESP8266 weird response to AT commands – Recently I bought an ESP8266ex from eBay. After setting up everything, I have a strange problem. The 8266 responds to AT commands, but responds with weird characters. I am using Arduino UNO. I connected the Tx pin of the Arduino to Rx pin of ESP8266 through a voltage divider (POT). GPI02 and RST pins are floating. The GPI02 is connected to ground through a 10k resistor. I have tried both 3.3v Arduino pin and ZR78L033 regulator to power up the 8266. But both ended up giving same output. Read more

RP measurement of eight motors continuously – I want to measure RPM of eight motors continuously, I have written a code, but the controller sometimes reads the previous sensor output and updates the succeeding sensor. Read more

Connecting to SIM900 via terminal – I finally got hold of three SIM9000 modules from various vendors  and am trying to do some basic tests on them with no luck. I am running TeraTerm on my laptop connected to the FTDI USB driver. The TX, RX, GND of  the FTDI module is connected to the SIM9000 module RX, TX and GND. If I give AT commands on the TeraTerm, I get no response back from the SIM9000 module. Is my basic setup correct? Read more

Interfacing PIC16F876A with driver L298 – I am trying to interface PIC micro 876A with stepper motor driver board built with the L298. I connected the stepper motor wires (bipolar) to the side connections of L298 and connected a 12v supply to the L298 board. I am left with 4 pin header to connect to micro. I just want to know how to run it in one complete rotation. Read more

Understanding the functionality of the Cypress PSoC 4 RTC library or C API routines – what is the meaning of parameters and Return Value int the following statement? Read more

void RTC_SetAlarmDateAndTime(const RTC_date_time * alarmTime)
Description:
Writes the time and date values as current alarm time and date.

Parameters:
alarmTime: Pointer to the RTC_date_time global structure where new values of alarm time and date are stored.

Return Value:
None