Maxim Integrated 71M6534 Energy Meter IC Family Software - Manual (Page 101)

71M653X Software User’s Guide
The push-button operation is very simple: Pressing the button wakes the part from LCD or sleep mode into brownout
mode. Afterward, a bit is set: IE_PB, bit 4 of IFLAGS, SFR E8.
One of the characteristics of the 71M653x is that it is not able to enter LCD or sleep mode if IE_PB or IE_WAKE (the
wake timer’s bit, see below) are set. The Demo Code clears these bits at the earliest convenient instant, transferring
their state to bits in the demo firmware’s status variable. This technique preserves data about how the chip last woke,
but also permits the chip to transition to the LCD and sleep modes easily.
V3P3SYS
rises
V3P3SYS
falls
MISSION
BROWNOUT
LCD
SLEEP or
V1 > VBIAS
V1 <= VBIAS
LCD_ONLY
RESET &
VBAT_OK
RESET
IE_PLLRISE
-> 1
IE_PLLFALL
- > 1
IE_PB - > 1
IE_WAKE ->
1
PB
timer
timer
PB
RESET &
V3P3SYS
rises
V3P3SYS
rises
VBAT_OK
VBAT_OK
VBAT_OK
VBAT_OK
SLEEP
Figure 5-5, State Diagram of Operating Modes
5.18 PORTING 71M6521 CODE TO THE 71M653X
5.18.1 Flash Use
The biggest issue when moving code from the 6521 to the 71M653x is the increased program memory. While the
71M6521 has 32K, most 653x series have at least 128K and the 71M6534 has 256K. The 653x defaults to a 64K
configuration, so code from earlier meter chips will fit easily.
Creating banked code that uses the extra flash is a substantial discussion in itself. See the section “Creating banked
code.”
5.18.2 Extra RAM
The MPU now has access to 4K of RAM, up from 2K. Roughly 1K is allocated to the CE, leaving 3K.
v1.1v1.1 TERIDIAN Proprietary 101 of 116
© Copyright 2005-2008 TERIDIAN Semiconductor Corporation