Datasheet

PN532_C1 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2017. All rights reserved.
Product data sheet
COMPANY PUBLIC
Rev. 3.6 — 28 November 2017
115436 37 of 222
NXP Semiconductors
PN532/C1
Near Field Communication (NFC) controller
When rewriting this formula, the value for the Timer1 reload value T1H is calculated from
the desired baud rate as follows:
Timer1 reload value T1H
(6)
One can achieve very low baud rates with Timer1 by leaving the Timer1 interrupt enabled,
and configuring the timer to run as a 16-bit timer (high nibble of T01MOD = 0001b), and
using the Timer1 interrupt to do a 16-bit firmware reload. Note: the frequency f
clk
is the
internal microcontroller frequency. If there is no clock divider then f
clk
= f
osc
.
For details on programming Timer1 to function as baud rate generator for the Debug
UART see Section 8.1.6 “
Timer0/1 description” on page 21.
The next table lists the maximum baud rates for using mode 2 of Timer1.
The next table shows commonly used baud rates using mode 2 of Timer1 and a CLK
frequency of 27.12 MHz.
Table 56. Maximum baud rates using mode 2 of Timer1
Reload value f
CLK
divided by SMOD Baud rate at f
CLK
Unit
6.78 13.56 27.12 MHz
FF 96 1 70.6 141.2 282.5 kb/s
Table 57. Baud rates using mode 2 of Timer1 with f
CLK
= 27.12 MHz
Reload value f
CLK
divided by SMOD Baud rate at f
CLK
Unit
FC 706 0 38.4 kb/s
F9 1412 0 19.2 kb/s
F1 2825 0 9.6 kb/s
E3 5650 0 4.8 kb/s
C5 11300 0 2.4 kb/s
8A 22600 0 1.2 kb/s
256
2
SMOD
f
clk

32 6 Baudrate
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