NXP Semiconductors PN544 C2 - Host Link Wake-Up from Standby Mode

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 55 of 172
9.3.2 Host Link Wake-up from Standby mode
When PN544 is in Standby mode, it is still possible to communicate with through the Host
link (HSU, I2C or SPI).
However it can happen that PN544 will not answer to the first frame sent. Host needs to
re-send the frame according to SHDLC definition (See [2])
1
2
(4) T1: Acknowledge time, T1 ≤5ms.
(5) T2: Guarding/transmit time, T2 ≥ T1+1ms.
(6) T3: Inactivity time, T3=1s.
Fig 31. PN544 Host Link wake-up
Step1: When receiving a frame on host link, PN544 can switch from Standby mode to
ActiveBAT mode. In case of T1 timeout, meaning that PN544 has not answered in time,
Host shall retransmit the frame in a delay from T2 to T3.
Step2: T3 timer is handled by PN544 to detect inactivity on Host Link. If there is no
more activity during T3, PN544 will switch back to Standby mode.
Note:
T3 timer is reset each time a frame is received by PN544. The T3 timeout value
can be changed by setting the TO_Before_SDTBY_MSB & TO_Before_SDTBY_LSB
EEPROM area. (See ‘0 chapter)
Note:
The T1 timeout value can be changed by setting the AckHostTimeout_LSB &
AckHostTimeout_MSB EEPROM area. (See ‘0 chapt
er)