Peer-to-peer, engineer-to-engineer questions and answers from the EDABoard.com engineering community around microcontrollers. Click the “Read more” link and follow the entire conversation and maybe add your two cents by logging in to EDAboard.com.

MCU does not boot on power up, only boots when reset button is pressed – I have a new design which is actually the second version, and this problem did not exist in the older version. I’m using an STM32F407GVT6 MCU with most of the peripherals that can be used including SPI, I2C, RS232, USART etc. The problem is when I plug the circuit, it does not boot automatically, yet when I press the reset button, it boots. I checked all the voltage levels, they are fine. I pulled down BOOT0 pin and pulled up BOOT1 (although BOOT1 is don’t care when BOOT0 is 0). Read more

How can I add a backup battery to keep my PIC microcontroller project working – I need to add a backup battery to keep my PIC microcontroller working when the main source goes down. Read more

Noise of driving relay from AVR – My AVR drives relay to switch ac lamp, I am using a circuit like the one below. The same output is used for an ac motor. When I connect the ac supply of loads the AVR enters interrupt, and the LCD changes and shows nothing. I used capacitor 1 uf on the +5 supply of the circuit. All the dc supply of control circuit and relay circuit is common. all the ground is common. Read more

LED fading with PWM + interrupt timer – Is it possible to implement timer interrupts to an LED fading PWM function? The reason why I need this is that I need to insert this function into another program which will change the PIC mode with LED blinking function (using interrupt timer as well). Read more

PIC16f72 pure sine wave inverter – Please help me with the correct hex file and circuit diagram of the PIC16f72 pure sine wave inverter. I built the circuit, loaded the hex file but I discovered that it does not have any data in the program memory and so only code memory is programmed. Read more

Latitude and longitude – I was searching 8051 gps programming. I don’t understand latitude and longitude. I found this link https://www.electronicshub.org/inter…crocontroller/ I don’t understand what’s happening in these two functions. Read more

True sinewave inverter output LC filter design – I have designed a true sinewave inverter for single phase 220V 50Hz. I am using 12V battery voltage to 325V DC VBUS voltage DC-DC converter (not shown in simulation). My SPWM is ok. The issue is I am not getting sinewave signal at the output. Read more

Interrupt during the context switching – If a high priority interrupt triggers while context switch for the low priority interrupt is in process (not completed), what will happen? Read more

Keypad function to return 0 to 16 characters – I need to display characters on the screen using a matrix keypad. I wrote code to print characters on the screen using the keypad but when I press any key program is not showing anything on the screen. I think there is a problem with my keypad function. Read more

Interfacing GSM module with PIC via mikroc pro – I have been trying to send SMS via PIC. I simulated it in Proteus to see if the PIC16F887 was actually transmitting and it worked out just fine. I used a voltage divider circuit to step down the output voltage of the Tx of the PIC to the Rx of the module but still didn’t work. I tried three diodes in series but didn’t work as well. Do I have to use MAX232 or there is another alternative? Read more