mfrc522 NXP Semiconductors, mfrc522 Datasheet - Page 58

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

NXP Semiconductors
112132
Product data sheet
Fig 18. I
2
C HS mode protocol switch
10.4.10 High Speed Transfer
10.4.11 Serial Data transfer Format in HS mode
10.4.9 HS mode
In High-speed mode (HS mode) the device can transfer information at data rates of up to
3.4 Mbit/s, it remains fully downward compatible with Fast- or Standard mode (F/S mode)
for bi-directional communication in a mixed-speed bus system.
To achieve a data rates of up to 3.4 Mbit/s the following improvements have been made to
the regular I
Serial data transfer format in HS mode meets the Standard mode I
HS mode can only commence after the following conditions (all of which are in F/S mode):
The active master then sends a repeated START condition (Sr) followed by a 7-bit slave
address with a R/W bit address, and receives an acknowledge bit (A) from the selected
MFRC522.
Data transfer continues in in Hs-mode after the next repeated START (Sr), and only
switches back to F/S-mode after a STOP condition (P). To reduce the overhead of the
master code, it's possible that a master links a number of Hs-mode transfers, separated
by repeated START conditions (Sr).
1. START condition (S)
2. 8-bit master code (00001XXX)
3. Not-acknowledge bit (A)
•
•
The inputs of the device in HS mode incorporates spike suppression and a
Schmitt-trigger at the SDA and SCL inputs with different timing constants compared to
F/S mode.
The output buffers of the device in HS mode incorporates slope control of the falling
edges of the SDA and SCL signals with different fall time compared to F/S mode.
2
C-bus behavior.
Rev. 3.2 — 22 May 2007
Contactless Reader IC
2
C-bus specification.
MFRC522
© NXP B.V. 2007. All rights reserved.
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