mfrc522 NXP Semiconductors, mfrc522 Datasheet - Page 60

• Manufacturer Part Number: mfrc522
• Description: Contactless Reader Ic
• Manufacturer: NXP Semiconductors

NXP Semiconductors
112132
Product data sheet
10.4.12 Switching from F/S to HS mode and Vice Versa
10.4.13 MFRC522 at Lower Speed modes
After reset and initialization, the MFRC522 is in Fast mode (which is in effect F/S mode as
Fast mode is downward compatible to Standard mode). The connected MFRC522
recognizes the “S 00001XXX A” sequence and switches its internal circuitry from the Fast
mode setting to the HS mode setting.
Following actions are taken:
For system configurations, where no other I
have an additional possibility to switch to HS-mode. By setting the bit I
register Status2Reg to logic 1, the HS mode is entered. Setting this bit to logic 1 changes
the HS-mode permanent meaning that sending the master code is no longer necessary.
This is not according the specification and should only be used when no other devices are
connected on the bus. Spikes on the I
spike suppression.
MFRC522 is fully downwards compatible, and can be connected to an F/S mode I
system. As no master code will be transmitted in such a configuration, the device stays in
F/S mode and communicates at F/S mode speeds.
1. Adapt the SDA and SCL input filters according to the spike suppression requirement
2. Adapt the slope control of the SDA output stages.
in HS mode.
Rev. 3.2 — 22 May 2007
2
C lines shall be avoided because of the reduced
2
C devices are involved in the communication,
Contactless Reader IC
MFRC522
2
© NXP B.V. 2007. All rights reserved.
CForceHS in
2
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C-bus