It is responsibility of design engineer to get the most performance and capability out of the resources available in limited budget and that too for specific application requirements.While the ideas presented here are around Atmel’s 89S52 microcontroller, these can be easily used with all other types of microcontrollers without any changes and configurations. This note discusses two such techniques to save microcontroller IO lines.Usually in order interface 3×2 keys i.e. 6 keys, we will need six IO pins of microcontroller to take inputs.However, in regular practice we usually recommend using matrix scanning method to interface more keys where keys are arranged in row-column format and then can be scanned one by one. In such case, we will need 3 rows and 2 columns (or vice versa) to interface 3×2 keys as shown in figure.
This very question stems from the need to cater application requirement as perfect as possible. When it comes to selecting a MCU based on parameters, almost all the manufacturers do provide parametric search engines / filters on their websites to choose the MCU from. However, most of the times the results from these filters are so much pointed that either you get a right choice or end up scratching your heads. In either case, these don’t help in just picking an MCU due to many other factors involved in selection. Let us see some of the critical consideration factors for selecting of MCU for an application