
ADSP-BF59x Blackfin Processor Hardware Reference
16-47
System Reset and Booting
PPI Boot Mode
The ADSP-BF59x processors feature a 16-bit PPI boot mode
(
BMODE
= 101). The PPI is a half-duplex bi-directional port consisting of
up to 16 data lines, 3 frame synchronization signals and a clock signal.
In PPI boot mode, the PPI mode of operation is configured as follows:
• Receive mode with 1 external frame sync
• 16-bit bus width
• Data sampled on falling edge of clock
• Frame sync configured for falling edge asserted
•
PPI_DELAY
value of 0x0
The external frame sync signal is on
PPI_FS1
. This signal is driven low by
the host at the start of a data transfer with a 16-bit word being transferred
on each
PPI_CLK
cycle that the
PPI_FS1
signal is asserted low.
In order to simplify the PPI host design, PPI boot mode also configures
Timer1 for PWM mode of operation. The PWM circuits of the timer are
configured to be clocked by the externally provided
PPI_CLK
signal allow-
ing for arbitrary pulse widths and pulse periods to be programmed thus
simulating an internally generated frame sync signal on the
PPI_FS2
signal.
This configuration lets the processor inform the host when the processor is
ready to receive data and also how much data is expected. This feature
removes the need for the host to process the actual contents of the boot
stream to identify the size of the data transfer.
The PPI host can synchronize the
PPI_FS2
signal to
PPI_CLK
signal and
initiate all data transfers accordingly. The
PPI_FS2
signal can be looped
back to the
PPI_FS1
. (See
Figure 16-15
.)
Summary of Contents for ADSP-BF59x Blackfin
Page 64: ...Development Tools 1 22 ADSP BF59x Blackfin Processor Hardware Reference...
Page 74: ...Processor Specific MMRs 2 10 ADSP BF59x Blackfin Processor Hardware Reference...
Page 244: ...Programming Examples 6 40 ADSP BF59x Blackfin Processor Hardware Reference...
Page 700: ...Programming Examples 16 78 ADSP BF59x Blackfin Processor Hardware Reference...
Page 738: ...Boundary Scan Architecture B 8 ADSP BF59x Blackfin Processor Hardware Reference...