NXP Semiconductors
UM191812
PN544 C2 User Manual
191812
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© NXP B.V. 2010. All rights reserved.
User Manual
Rev. 1.2 — 2010-06-16
57 of 172
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If
Vbat<VbatCritical
, PN544 is able to supply Secure Element and switch
automatically in ‘Power by the field’ (No battery resources needed).
9.4 Clock Management
This chapter describes the clock setup, the clock request and acknowledge in the case of
a clock provided by the system (Baseband, PMU, Host Controller …) to the PN544.
Clock management is a combination of request & acknowledge. The system has to setup
the way it wants the PN544 to request the clock, and the way to give back acknowledge
to PN544.
To setup the Clock, some EEPROM data have to be set:
PlClockRequest
,
PlClockAck
,
PlClockTimeout
,
FRAC_ClkSel
and
FRAC4_xxx
.
The
‘PollingLoopMgt’
gate has to be used to manage HCI events.
(
Refer to the
‘PollingLoopMgt’
and
‘0
chapters for details
)
9.4.1 Clock Setup
PN544 can use the clock provided by an external oscillator or request the clock from the
mobile platform.
9.4.1.1 Use of external oscillator
To setup the use of external oscillator (Crystal/Quartz), the following EEPROM area has
to be set:
Table 49. Setting for external oscillator
Name
Length
(bytes)
Value(s)
Comments
HW_Conf
1
Bit7 set to 1.
(Default value)
Disable the Use of
internal FracNPLL
FRAC_ClkSel
1
0
No input clock
Note: No others settings are required for this configuration. It means that the following
setup are not needed and not taken into account by PN544.