The device is accessed through a multiplexed byte-wide interface, which supports both Intel and Motorola modes. A lithium coin-cell battery can be connected to the VBAT input pin on the DS12885 to maintain time and date operation when primary power is absent.
If a primary power failure is detected, the device automatically switches to a backup supply. A precision temperature-compensated circuit monitors the status of VCC. The devices also operate in either 24-hour or 12-hour format with an AM/PM indicator. For all devices, the date at the end of the month is automatically adjusted for months with fewer than 31 days, including correction for leap years. The DS12C887 adds a century byte at address 32h. The DS12887 integrates a quartz crystal and lithium energy source into a 24-pin encapsulated DIP package.
The devices provide a real-time clock/calendar, one time-of-day alarm, three maskable interrupts with a common interrupt output, a programmable square wave, and 114 bytes of battery backed static RAM (113 bytes in the DS12C887 and DS12C887A). The DS12885, DS12887, and DS12C887 real-time clocks (RTCs) are designed to be direct replacements for the DS1285 and DS1287.
peterjohnson259085 wrote a comment on Magic Flying Solar Carpet. #Dallas ds12887 real time clock Pc
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Mark B Jones liked Echo Sounder Buoys: Upcycling Playbook. guilhermeherzog liked OpenSCAD.cloud Browser based openSCAD environment. Rupert Hirst wrote a reply on Gnat-Stats Tiny OLED PC Performance Monitor. 555Techlab wrote a reply on Adjustable Voltage Reference with OPAMP 741. Steph has updated the log for GlowStitch LED Strips. Gregg Eshelman on This Camera Does Not Exist. JohnU on Powerful Water Pump Is Modular In Nature. Nick on A Call For Better Shower Temperature Controls. JohnU on Is This The World’s Largest Dot Matrix Printer?. Ewald on A More Conspicuous Computer Assistant. JohnU on The Many Robots That Ventured Into The Chernobyl NPP #4 Reactor. MS-BOSS on Electronic Earrings Are PCB Art You Can Wear. Posted in Repair Hacks, Retrocomputing Tagged DS12885, DS12887, real time clock battery Post navigationĪsk Hackaday: The Turing Test Is Dead: Long Live The Turing Test! 85 Comments Someone in the comments mentioned liquid electrical tape, but we might have been tempted to just coat it with hot glue or - if we didn’t want to take it apart - epoxy. In the second video, he uses clear nail polish to protect the exposed wires. It looks like a hack, but then that’s the way we like it. The board fits on top of the IC - technically, it is more of a module than an IC - and solders to some contacts exposed by the Dremel surgery. The DS12C887 adds a century byte at address 32h. You also need to disconnect the dead battery which requires a Dremel and a steady hand. DS12887, DALLAS SEMICONDUCTOR, Real Time Clock, Non-Volatile, 1 Timer(s). However, the board is only part of the problem. DS12887, Analog Devices Inc./Maxim Integrated, IC RTC CLK/CALENDAR PAR 24-EDIP. 
The repair used a PCB he ordered from Tindie. However, he actually had the DS12887, which has an internal oscillator, something the second video explains. In the first video, he replaces both the battery and adds an external oscillator which would be necessary for the DS12885. wanted to restore a machine that used one of these devices and was able to repair the device. The problem, of course, is that batteries die. For example, the Dallas DS12885 and DS12887 real time clock “chips” were available in a large package with an internal battery. You can find a lot of strange things inside IC packages.
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