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Table 47-15. DMA configuration
Flag
Request enable bit
DMA select bit
TDRE
TIE = 1
TDMAS = 1
RDRF
RIE = 1
RDMAS = 1
When a flag is configured for a DMA request, its associated DMA request is asserted
when the flag is set. When S1[RDRF] is configured as a DMA request, the clearing
mechanism of reading S1, followed by reading D, does not clear the associated flag. The
DMA request remains asserted until an indication is received that the DMA transactions
are done. When this indication is received, the flag bit and the associated DMA request is
cleared. If the DMA operation failed to remove the situation that caused the DMA
request, another request is issued.
47.8 Application information
This section describes the UART application information.
47.8.1 Transmit/receive data buffer operation
47.8.2 ISO-7816 initialization sequence
This section outlines how to program the UART for ISO-7816 operation. Elements such
as procedures to power up or power down the smartcard, and when to take those actions,
are beyond the scope of this description. To set up the UART for ISO-7816 operation:
1. Select a baud rate. Write this value to the UART baud registers (BDH/L) to begin the
baud rate generator. Remember that the baud rate generator is disabled when the
baud rate is zero. Writing to the BDH has no effect without also writing to BDL.
According to the 7816 specification the initial (default) baud rating setting should be
Fi = 372 and Di = 1 and a maximum frequency of 5 MHz. In other words, the BDH,
BDL, and C4 registers should be programmed such that the transmission frequency
provided to the smartcard device must be 1/372th of the clock and must not exceed 5
MHz.
2. Write to set BDH[LBKDIE] = 0.
3. Write to C1 to configure word length, parity, and other configuration fields (LOOPS,
RSRC) and set C1[M] = 1, C1[PE] = 1, and C1[PT] = 0.
Application information
K22F Sub-Family Reference Manual, Rev. 4, 08/2016
1294
NXP Semiconductors
Содержание K22F series
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Страница 168: ...Module clocks K22F Sub Family Reference Manual Rev 4 08 2016 168 NXP Semiconductors...
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Страница 1040: ...Example configuration for chained timers K22F Sub Family Reference Manual Rev 4 08 2016 1040 NXP Semiconductors...
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