How to test crystal oscillators

This post is about a simple circuit to test crystal oscillators . They are found in most of the RF and processing circuitry as an external component to provide clocking, time reference for synchronization of internal system operations. testing them isn't that straight forward by connecting its terminals to a multimeter or an oscilloscope. This is an interesting test circuit for crystals in 1MHz - 30MHz range with 2 NPN transistors, Zeners, some passives, and thought of testing a few crystals.
When the DUT crystal oscillates, the signal passes through the 1nF loading capacitor to the two Zeners, thereby charging the 4.7nF capacitor and turns on the second transistor which in turn illuminates the LED, indicating that it's all good!

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What is the ESP32 VSPI / HSPI

The ESP32 integrates four SPI peripherals. SPI0 and SPI1 are used to access the ESP32’s attached flash memory and thus are currently not open to users to be used . They share one signal bus via an arbiter. SPI2 and SPI3 are general purpose SPI controllers, sometimes referred to as HSPI and VSPI, respectively. They are open for use. SPI2 and SPI3 have independent signal buses with the same respective names. Each bus has three CS lines to drive up to three SPI slaves.

Most common baud rates table

The following table shows the most used baud rates. The left side part of the table shows speed and bit duration. The right part shows real transmission speed assuming there is no parity, 8 data bits and one stop bit. Bauds Bits/s Bit duration Speed Actual speed Actual byte duration 50 bauds 50 bits/s 20.000 ms 6.25 bytes/s 5 bytes/s 200.000 ms 75 bauds 75 bits/s 13.333 ms 9.375 bytes/s 7.5 bytes/s 133.333 ms 110 bauds 110 bits/s 9.091 ms 13.75 bytes/s 11 bytes/s 90.909 ms 134 bauds 134 bits/s 7.463 ms 16.75 bytes/s 13.4 bytes/s 74.627 ms 150 bauds 150 bits/s 6.667 ms 18.75 bytes/s 15 bytes/s 66.667 ms 200 bauds 200 bits/s 5.000 ms 25 bytes/s 20 bytes/s 50.000 ms 300 bauds 300 bits/s 3.333 ms 37.5 bytes/s 30 bytes/s 33.333 ms 600 bauds 600 bits/s 1.667 ms 75 bytes/s 60 bytes/s 16.667 ms 1200 bauds 1200 bits/s 833.333 µs 150 bytes/s 120 bytes/s 8.333 ms 1800 bauds 1800 bits/s 555.556 µs 225...

How to program 8051 based MCU using Ptroteous Schematic capture and Source code editor to use timers using AT892051 + project files

This tutorial is dedicated to use a 8051 based Microcontroller core and program it using keil's C51 tools on the Proteus Source code editor. 1- Brief History of 8051 one of the first microprocessors 4004 was invented by Intel Corporation as well as 8085 and 8086 microprocessors back in 1981,shortly after Intel introduced an 8-bit microcontroller called the 8051 . It was referred to as system on a chip because it had 128 bytes of RAM, 4K byte of on-chip ROM, two timers, one serial port, and 4 ports (8-bit wide), all on a single chip. When it became so widespread, Intel allowed other manufacturers to make and market different flavors of 8051 with its code compatible with 8051. It means that if you write your program for one flavor of 8051, it will run on other flavors too, regardless of the manufacturer. This has led to several versions with different speeds and amounts of on-chip RAM. 2- Features of AT892051 Microcontroller Compatible with MCS®-51Products 2K ...

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