NXP Semiconductors PN544 C2 - Guard Host Timeout

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 25 of 172
7.4.5.2 Guard Host Timeout
This timeo
ut defines the maximum time the Host has to acknowledge a frame received.
When timeout is reached, PN544 resends the frame. It is used with HSU interface.
(1) T: Guard Timeout Host
Fig 17. PN544 Guard Host Timeout
Case Communication OK: After sending a frame to the host PN544 starts an internal
timer, waiting for the frame to be acknowledged by the host. The ACK is received in-time
and PN544 will proceed sending the next frame.
Case Communication KO: Timer is started after frame was sent but no ACK is
received in-time. -> Timeout triggers PN544 to resend the frame to the host.
The number of retries is defined in EEPROM as Host_Rx_Retry and Host_Tx_Retry.
Guard Host Timeout value can be changed by setting the GuardHostTimeoutMSB &
GuardHostTimeoutLSB EEPROM area. (See
HW configuration chapter).
Note:
To disable the resend mechanism, the timeout has to be set to NULL value.