TMS320VC5504 datasheet(93/128 Pages) TI

93 / 128 page

6.11 Real-Time Clock (RTC)

TMS320VC5504

Fixed-Point Digital Signal Processor

www.ti.com

SPRS609A – JUNE 2009 – REVISED JULY 2009

The VC5504 includes a Real-Time Clock (RTC) with its own separated power supply and isolation circuits.

The separate supply and isolation circuits allow the RTC to run while the rest of the VC5504 device (Core

and I/O) is powered off. All RTC registers are preserved (except for RTC Control and RTC Update

Registers) and the counter continues to operate when the device is powered off. The RTC also has the

capability to wakeup the device from idle states via alarms, periodic interrupts, or an external WAKEUP

input. Additionally, the RTC is able to output an alarm or periodic interrupt on the WAKEUP pin to cause

external power management to re-enable power to the DSP Core and I/O.

The VC5504 RTC provides the following features:

• 100-year calendar up to year 2099.

• Counts seconds, minutes, hours, day of the week, date, month, and year with leap year compensation

• Millisecond time correction

• Binary-coded-decimal (BCD) representation of time, calendar, and alarm

• 24-hour clock mode

• Second, minute, hour, day, or week alarm interrupt

• Periodic interrupt: every millisecond, second, minute, hour, or day

• Alarm interrupt: precise time of day

• Single interrupt to the DSP CPU

• 32.768-kHz crystal oscillator with frequency calibration

Control of the RTC is maintained through a set of I/O memory mapped registers (see Table 6-19). Note

that any write to these registers will be synchronized to the RTC 32.768-KHz clock; thus, the CPU must

run at least 3X faster than the RTC. Writes to these registers will not be evident until the next two

32.768-KHz clock cycles later. Furthermore, if the RTC Oscillator is disabled, no RTC register can be

written to.

The RTC has its own power-on-reset (POR) circuit which resets the registers in the RTC core domain

when power is first applied to the CVDD_RTC power pin. The RTC flops are not reset by the device'sRESET

pin nor the digital core's POR (powergood signal) which monitors the DSP_LDOO voltage.

The scratch registers in the RTC can be used to take advantage of this unique reset domain to keep track

of when the DSP boots and whether the RTC time registers have already been initialized to the current

clock time or whether the software needs to go into a routine to prompt the user to set the time/date.

Submit Documentation Feedback

Peripheral Information and Electrical Specifications

TMS320VC5504 Datasheet(PDF) 93 Page - Texas Instruments