Maxim Integrated MAXQ622 User Manual

Page 83

MAXQ612/MAXQ622 User’s Guide

5-10

Maxim Integrated

DESCRIPTION

PO6 (02h, 01h)

Port 6 Output Register (8-bit register)

Initialization:

This register is set to 00h on all forms of reset .

Read/Write Access:

Unrestricted read/write .

PO6.7 to PO6.0

Port 6 Output Register Bits 7:0. The PO6 register stores output data for port 64 when it is

defined as an output port and controls whether the internal weak p-channel pullup transistor
is enabled/disabled if a port pin is defined as an input . The contents of this register can be
modified by a write access . Reading from the register returns the contents of the register .
Changing the direction of port 6 does not change the data contents of the register .

WUTC (04h, 01h)

Wake-Up Timer Control Register (8-bit register)

Initialization:

This register is cleared to 00h on all resets .

Read/Write Access:

Unrestricted read/write access except that bit 1 is read-only .

WUTC.0 (WTE)

Wake-Up Timer Enable. This control bit enables down counting of the 16-bit wake-up

timer . Clearing this bit resets the internal wake-up timer down counter and resets WTF =
0 . When WTE = 0, the initial down-counter starting value written into the WUT register is
accessed on WUT register reads . Setting this bit from 0 to 1 loads the internal down counter
with the initial value written to the WUT register, and enables down counting of the wake-up
timer using the ring oscillator . When WTE = 1, the internal down counter value is accessed
on WUT register reads . When WTE = 1, hardware setting of the WTF bit can generate an
interrupt request to the CPU if also enabled globally .

WUTC.1 (WTF)

Wake-Up Timer Flag. This bit serves as a status bit/interrupt flag to denote when the wake-

up timer down count has reached 0h . Hardware sets this bit whenever the wake-up down
counter reaches 0h . The WTF bit is cleared by hardware any time the WTE bit is changed
from 1 to 0 .

WUTC.7 to WUT.2

Reserved . Reads return 0 .

WUT (05h, 01h)

Wake-Up Timer Register (16-bit register)

Initialization:

This register is cleared to 0000h on all resets .

Read/Write Access:

Unrestricted write access .
When WTE = 0, reads access the initial starting value written to WUT . When WTE = 1, reads
access the internal down counter, thus multiple reads should be made to attain a stable
value

WUT.15 to WUT.0

Wake-Up Timer Value Register Bits 15:0. These bits reflect the 16 bit value of the Wake-

Up Timer . When WTE = 0, the initial wake-up timer starting value may be accessed by
reads and writes of the WUT register . This initial starting value is retained internally so that
triggering another wake-up timer interval requires only toggling of the WTE bit 1 ≥ 0 ≥ 1 .
When WTE = 1, the internal down-counter value is accessed by reads of WUT, however,
write access is still directed to the initial starting value (that is loaded to the down counter
each time WTE is changed 0 ≥ 1) . The 16-bit wake-up timer counts downward until reaching
0h unless disabled . The internal down counter is asynchronously reset to 0 anytime the
wake-up timer is disabled by clearing WTE = 0 . Once started, the WTF flag is set by
hardware when the down count reaches 0h . The 0FFFFh starting state for the WUT[15:0]
bits yield the maximum possible down-count range . Writing the WUT[15:0] bits establishes
the down-count starting values shown below:

WUT[15:0]

DOWN-COUNT START VALUE

0001h

0002h

0003h

0004h

--Other--

(WUT[15:0])

0FFFEh

- 2) = 65,534

0FFFFh

- 1) = 65,535

This manual is related to the following products:

MAXQ612