A General-Purpose Serial Communication Interface for the MMC2001 Using the Motorola API

PublishTime：2022-04-26

Even though many microcontrollers (MCU) have an integrated UART(universal asynchronous receiver transmitter) on board, some customers may need another one. For instance, if the part has only one UART, they may need two.
One way to overcome this problem is to design a software UART, also called SCI (serial communication interface). This is feasible if the MCU has a general-purpose timer like the MMC2001 MCU does, with its six independent PWMs (pulse-width modulator).
This application note describes a software (SW) UART, written in C language. It has been developed for the MMC2001, a M•CORE MCU. Because it is a program written in a high-level language,the SW UART can be adapted easily to other cores like PowerPC and 68HCxx.
This SCI is designed for an 8-bit data, one start bit, one stop bit, least significant bit (LSB) first protocol, which is probably the most common configuration. The baud rate (bits per second) can vary up to a maximum of 19,200 baud. The protocol needs to be set before establishing a communication link. The SCI can communicate only in half-duplex mode. This means it can either transmit or receive, but it cannot do both functions simultaneously.
For more information, several application notes describe the RS-232 protocol, including "HC05 MCU Software-Driven Asynchronous Serial Communication Techniques Using MC68HC705J1A," document order number AN1240/D; "Software SCI Implementation to the MISC Communication Protocol," number AN1667/D; and "Software SCI Routines with the 16-Bit Timer Module," order number AN1818/D.

Brand of Product：	NXP
Part#：	MMC2001 、 68HCxx 、 MC68HC705J1A 、 MMC2003 、 MMC2080 、 MMC2107 、 M68HC05 Family 、 M68HC05 More Part#
Product Category：	microcontrollers 、 MCU More
Application：	More
Data Type：	Application note & Design Guide More
Safety & Environment Standards：	More
Operating Temperature：	Please see the document for details
Qualification Grade：	More
Qualification Approval：	More
Package：
Language：	English Chinese Chinese and English Japanese
Date of Creation：	2006/5/2
Version Number：
Data Encoding：	AN2025
Data Size：	439 KB

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