71M6534 MAXIM [Maxim Integrated Products], 71M6534 Datasheet - Page 66

• Manufacturer Part Number: 71M6534
• Description: Exceeds IEC 62053/ANSI C12.20 Standards
• Manufacturer: MAXIM [Maxim Integrated Products]

2.5.2 Wake on Timer
If the part is in SLEEP or LCD mode, it can be awakened by the wake-up timer. Until this timer times out,
the MPU is in reset due to WAKE being low. When the wake-up timer times out, the WAKE signal rises
and within three CK32 cycles, the MPU begins to execute. The MPU can determine whether the timer
woke it by checking the AUTOWAKE interrupt flag (IE_WAKE).
The wake-up timer begins timing when the part enters LCD or SLEEP mode. Its duration is controlled by
WAKE_PRD[2:0] and WAKE_RES. WAKE_RES selects a timer LSB of either 1 minute (WAKE_RES = 1) or
2.5 seconds (WAKE_RES = 0). WAKE_PRD[2:0] selects a duration of from 1 to 7 LSBs.
The timer is armed by WAKE_ARM = 1. It must be armed at least three RTC cycles before SLEEP or
LCD_ONLY is initiated. Setting WAKE_ARM presets the timer with the values in WAKE_RES and WAKE_PRD
and readies the timer to start when the processor writes to the SLEEP or LCD_ONLY bits. The timer is
reset and disarmed whenever the processor is awake. Thus, if it is desired to wake the MPU periodically
(every 5 seconds, for example) the timer must be rearmed every time the MPU is awakened.
2.6 Data Flow
The data flow between the Compute Engine (CE) and the MPU is shown in
the 32-bit CE sequentially processes the samples from the voltage inputs on pins IA, VA, IB, and VB,
performing calculations to measure active power (Wh), reactive power (VARh), A
metering. These measurements are then accessed by the MPU, processed further and output using the
peripheral devices available to the MPU.
66
(V3P3SYS)
MPU Mode
PB or wake-
PLL_OK
System
WAKE
Power
up timer
Samples
LCD
Pulses
Processor
I/O RAM (Configuration RAM)
CE
Pre -
Figure 29: MPU/CE Data Flow
Figure 28: Wake Up Timing
Figure 29
15 CK32
cycles
IRQ
Data
BROWNOUT
illustrates the CE/MPU data flow.
Processor
MPU
Post -
Processed
Figure
Metering
Data
2
h, and V
29. In a typical application,
time
2
h for four-quadrant
Rev 2