NXP Semiconductors
UM191812
PN544 C2 User Manual
191812 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2010. All rights reserved.
User Manual Rev. 1.2 — 2010-06-16 66 of 172
The acknowledge mechanism using HCI event is described in the following figure:
Host Link
(I2C, SPI, ..)
System Clock
1
NXP_EVT_CLK_ACK
2
(1)
Fig 40. Clock acknowledge with HCI event
Step1: PN544 request the clock from the system (for clock request, see previous
chapter: ‘Clock Request & Release’).
Step2: When the system clock is available, Host controller sends the
NXP_EVT_CLK_ACK event. PN544 is informed that clock is available & stable.
Note: Whatever the Clock Acknowledge method used, the timeout will ever trigger the
acknowledgment. It means PN544 always consider the timeout as the maximum
allowed time to acknowledge.
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