ADSP-BF537 Blackfin Processor Hardware Reference
19-57
System Reset and Booting
bytes until it has received the complete acknowledge string. Once the
0x00
byte has been received, the host can send the entire boot stream at once.
The host should know the total byte count of the boot stream, but it is not
required to have any knowledge about the content of the boot stream.
When the boot kernel is processing ZEROFILL or INIT blocks it might
require extra processing time and needs to hold the host off from sending
more data. This is signalled with the
HWAIT
output which can operate on
any GPIO of port G. The GPIO which is actually used is encoded in the
FLAG word of all block headers. See
details. The boot kernel is not permitted to drive any of the GPIOs before
the first block header has been received and evaluated completely. There-
fore, a pulling resistor on the
HWAIT
signal is recommended. If the resistor
pulls down to ground, the host is always permitted to send when the
HWAIT
signal is low and must pause transmission when
HWAIT
is high. The Black-
fin UART module does not provide extremely large receive FIFOs, so the
host is requested to test
HWAIT
at every transmitted byte.
As indicated in
HWAIT
feedback may connect to the
Clear-To-Send (CTS) input of an EIA-232E compatible host device,
resulting in a subset of a so-called hardware handshake protocol. At boot
time the Blackfin does not evaluate any Request-To-Send (RTS) signal
driven by the host.
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 ...