![]() ![]() Background īCD takes advantage of the fact that any one decimal numeral can be represented by a four-bit pattern. However, decimal fixed-point and decimal floating-point formats are still important and continue to be used in financial, commercial, and industrial computing, where the subtle conversion and fractional rounding errors that are inherent in binary floating point formats cannot be tolerated. BCD per se is not as widely used as in the past, and is unavailable or limited in newer instruction sets (e.g., ARM x86 in long mode). Its principal drawbacks are a slight increase in the complexity of the circuits needed to implement basic arithmetic as well as slightly less dense storage.īCD was used in many early decimal computers, and is implemented in the instruction set of machines such as the IBM System/360 series and its descendants, Digital Equipment Corporation's VAX, the Burroughs B1700, and the Motorola 68000-series processors. īCD's main virtue, in comparison to binary positional systems, is its more accurate representation and rounding of decimal quantities, as well as its ease of conversion into conventional human-readable representations. The ten states representing a BCD digit are sometimes called tetrades (for the nibble typically needed to hold them is also known as a tetrade) while the unused, don't care-states are named pseudo-tetrad(e)s, pseudo-decimals or pseudo-decimal digits. The precise 4-bit encoding, however, may vary for technical reasons (e.g. most modern computers), the term unpacked BCD usually implies a full byte for each digit (often including a sign), whereas packed BCD typically encodes two digits within a single byte by taking advantage of the fact that four bits are enough to represent the range 0 to 9. Sometimes, special bit patterns are used for a sign or other indications (e.g. In computing and electronic systems, binary-coded decimal ( BCD) is a class of binary encodings of decimal numbers where each digit is represented by a fixed number of bits, usually four or eight. In this clock, each column of LEDs shows a binary-coded decimal numeral of the traditional sexagesimal time. You should have received a copy of the GNU Lesser General Public License along with this library if not, write to the Free Software Foundation, Inc.A binary clock might use LEDs to express binary values. See the GNU Lesser General Public License for more details. This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. This library is free software you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation either version 2.1 of the License, or (at your option) any later version. ![]() Changed class to MD_DS1307 and standardised on lower letter case 1st letter for method names.Ĭopyright (C) 2015 Marco Colli.Fixed bug in setting the time when in 12 hour mode.Changed examples to remove 'deprecated' compiler warning.Added overloaded constructor specifying sca and scl.Cleaned up dependency on ESP8266 for constructor change.Control of clock features (on/off, 12/24H, day of week).Control of square wave generator (on/off & frequency).Read/write clock and alarm registers as RAM.Read and write alarm registers and controls.Access to the 64 byte battery backed up RAM.This library features access to all on-chip features has and frequency programmable square-wave output. ![]() operates in either the 24-hour or 12-hour format with an AM/PM indicator.automatically adjusts dates for months with fewer than 31 days, including corrections for leap year.maintains seconds, minutes, hours, day, date, month, and year information.incorporates a battery input, and maintains timekeeping when main power to the device is interrupted.Microprocessor interface is exclusively through an I2C bidirectional bus. The DS1307 serial real-time clock (RTC) is a low-power, full binary-coded decimal (BCD) clock/calendar plus 56 bytes of non-volatile SRAM. ![]()
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