Motorola 68hc11 • 1.

Contents • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • Brief history [ ] The AVR architecture was conceived by two students at the (NTH), Alf-Egil Bogen and Vegard Wollan. The original AVR MCU was developed at a local house in, called Nordic VLSI at the time, now, where Bogen and Wollan were working as students. [ ] It was known as a μRISC (Micro RISC) [ ] and was available as silicon IP/building block from Nordic VLSI.

[ ] When the technology was sold to Atmel from Nordic, the internal architecture was further developed by Bogen and Wollan at Atmel Norway, a subsidiary of Atmel. The designers worked closely with compiler writers at to ensure that the AVR instruction set provided efficient of. Atmel says that the name AVR is not an acronym and does not stand for anything in particular. The creators of the AVR give no definitive answer as to what the term 'AVR' stands for. However, it is commonly accepted that AVR stands for Alf and Vegard's RISC processor. Note that the use of 'AVR' in this article generally refers to the 8-bit RISC line of Atmel AVR Microcontrollers. Among the first of the AVR line was the AT90S8515, which in a 40-pin DIP package has the same pinout as an microcontroller, including the external multiplexed address and data bus.

Next: LCD display for the Up: Serial Communication Previous: RS-232 Serial Protocol. Motorola 68HC11 SCI Interface. The Motorola 68HC11 supports one SCI. We'll discuss both transmitting and receiving ends of the SCI. The programmer controls the operation of the SCI interface through a set of hardware registers that. This section contains a description of the serial communication interface (SCI). 5.1 Overview and Features. A full-duplex asynchronous Serial Communications Interface (SCI) is provided with a standard NRZ format (one start. MC68HC1 1A8 SERIAL COMMUNICATIONS INTERFACE MOTOROLA. TECHNICAL DATA 5–1.

The polarity of the RESET line was opposite (8051's having an active-high RESET, while the AVR has an active-low RESET), but other than that the pinout was identical. The AVR 8-bit microcontroller architecture was introduced in 1997. By 2003, Atmel had shipped 500 million AVR flash microcontrollers. The platform for simple electronics projects was released in 2005 and featured ATmega8 AVR microcontrollers. Device overview [ ] The AVR is a machine, where program and data are stored in separate physical memory systems that appear in different address spaces, but having the ability to read data items from program memory using special instructions. Basic families [ ] AVRs are generally classified into following: • tinyAVR – the ATtiny series.

Main article: In 2006, Atmel released microcontrollers based on the 32-bit architecture. This is a completely different architecture unrelated to the 8-bit AVR, intended to compete with the -based processors. Shreve Chemical Process Industries 5th Edition Free Download. It has a 32-bit data path, and instructions, along with other audio- and video-processing features. The instruction set is similar to other RISC cores, but it is not compatible with the original AVR (nor any of the various ARM cores). Device architecture [ ],, and are all integrated onto a single chip, removing the need for external memory in most applications. Some devices have a parallel external bus option to allow adding additional data memory or memory-mapped devices.

Almost all devices (except the smallest TinyAVR chips) have serial interfaces, which can be used to connect larger serial EEPROMs or flash chips. Program memory [ ] Program instructions are stored in. Although the are 8-bit, each instruction takes one or two 16-bit words. The size of the program memory is usually indicated in the naming of the device itself (e.g., the ATmega64x line has 64 KB of flash, while the ATmega32x line has 32 KB). There is no provision for off-chip program memory; all code executed by the AVR core must reside in the on-chip flash. However, this limitation does not apply to the AT94 FPSLIC AVR/FPGA chips.

Internal data memory [ ] The data consists of the, I/O registers, and. Some small models also map the program ROM into the data address space, but larger models do not. Internal registers [ ].

Atmel ATxmega128A1 in 100-pin package The AVRs have 32 and are classified as 8-bit RISC devices. In the tinyAVR and megaAVR variants of the AVR architecture, the working registers are mapped in as the first 32 memory addresses (0000 16–001F 16), followed by 64 I/O registers (0020 16–005F 16). In devices with many peripherals, these registers are followed by 160 “extended I/O” registers, only accessible as (0060 16–00FF 16). Actual SRAM starts after these register sections, at address 0060 16 or, in devices with 'extended I/O', at 0100 16. Even though there are separate addressing schemes and optimized opcodes for accessing the register file and the first 64 I/O registers, all can also be addressed and manipulated as if they were in SRAM. The very smallest of the tinyAVR variants use a reduced architecture with only 16 registers (r0 through r15 are omitted) which are not addressable as memory locations.