ADSP-BF537 Blackfin Processor Hardware Reference
13-7
UART Port Controllers
If enabled by the
ERBFI
bit in the
UARTx_IER
register, a 0 to 1 transition of
the
DR
flag requests an interrupt on the dedicated
RXREQ
output. This sig-
nal is routed through the DMA controller. If the associated DMA channel
is enabled, the
RXREQ
signal functions as a DMA request, otherwise the
DMA controller simply forwards it to the SIC interrupt controller.
If errors are detected during reception, an interrupt can be requested to a
separate error interrupt output. This error request goes directly to the SIC
interrupt controller. However, it is hard-wired with the error requests of
other modules. The error handler routine may need to interrogate multi-
ple modules as to whether they requested the event. Error requests must
be enabled by the
ELSI
bit in the
UARTx_IER
register. The following error
situations are detected. Every error has an indicating bit in the
UARTx_LSR
register.
• Overrun error (
OE
bit)
• Parity error (
PE
bit)
• Framing error/Invalid stop bit (
FE
bit)
• Break indicator (
BI
bit)
Reception is started when a falling edge is detected on the RX input pin.
The receiver attempts to see a start bit. For better immunity against noise
and hazards on the line, the receiver oversamples every bit 16 times and
does a majority decision based on the mid three samples. The data is
shifted immediately into the internal
RSR
register. After the 9th sample of
the first stop bit is processed, the received data is copied to the
UARTx_RBR
register and the receiver recovers itself for further data.
The sampling clock equal to 16 times the bit rate samples the data bits
close to their midpoint. Because the receiver clock is usually asynchronous
to the transmitter’s data rate, the sampling point may drift relative to the
center of the data bits. The sampling point is synchronized again with
Summary of Contents for Blackfin ADSP-BF537
Page 42: ...Contents xlii ADSP BF537 Blackfin Processor Hardware Reference ...
Page 90: ...Development Tools 1 32 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 138: ...Programming Examples 4 26 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 340: ...SDC Programming Examples 6 84 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 606: ...Programming Examples 9 94 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 660: ...Programming Examples 10 54 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 720: ...Electrical Specifications 11 60 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 840: ...Programming Examples 13 42 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 876: ...Programming Examples 14 36 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 938: ...Programming Examples 15 62 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 958: ...Programming Examples 17 12 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 986: ...Programming Examples 18 28 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 1162: ...G 26 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 1218: ...Index I 56 ADSP BF537 Blackfin Processor Hardware Reference ...