Rev. F
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Page 15 of 64
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October 2013
EMU
O (O/D, pu)
Emulation Status. Must be connected to the ADSP-21367/ADSP-21368/
ADSP-21369 Analog Devices DSP Tools product line of JTAG emulator target board con-
nectors only.
CLK_CFG1–0
I
Core/CLKIN Ratio Control. These pins set the start-up clock frequency. See the processor
hardware reference for a description of the clock configuration modes.
Note that the operating frequency can be changed by programming the PLL multiplier
and divider in the PMCTL register at any time after the core comes out of reset.
CLKIN
I
Local Clock In. Used with XTAL. CLKIN is the processor’s clock input. It configures the
processors to use either its internal clock generator or an external clock source. Connect-
ing the necessary components to CLKIN and XTAL enables the internal clock generator.
Connecting the external clock to CLKIN while leaving XTAL unconnected configures the
processor to use an external clock such as an external clock oscillator. CLKIN may not be
halted, changed, or operated below the specified frequency.
XTAL
O
Crystal Oscillator Terminal. Used in conjunction with CLKIN to drive an external crystal.
RESET
I
Processor Reset. Resets the processor to a known state. Upon deassertion, there is a 4096
CLKIN cycle latency for the PLL to lock. After this time, the core begins program execution
from the hardware reset vector address. The RESET input must be asserted (low) at power-
up.
RESETOUT
ODriven low/
driven high
Reset Out. Drives out the core reset signal to an external device.
BOOT_CFG1–0
I
Boot Configuration Select. These pins select the boot mode for the processor. The
BOOT_CFG pins must be valid before reset is asserted. See the processor hardware
reference for a description of the boot modes.
BR4–1
Pulled high/
pulled high
External Bus Request. Used by the ADSP-21368 processor to arbitrate for bus master-
ship. A processor only drives its own BRx line (corresponding to the value of its ID2-0
inputs) and monitors all others. In a system with less than four processors, the unused BRx
pins should be tied high; the processor’s own BRx line must not be tied high or low
because it is an output.
ID2–0
I (pd)
Processor ID. Determines which bus request (BR4–1) is used bythe ADSP-21368 processor.
ID = 001 corresponds to BR1, ID = 010 corresponds to BR2, and so on. Use ID = 000 or 001
in single-processor systems. These lines are a system configuration selection that should
be hardwired or only changed at reset. ID = 101,110, and 111 are reserved.
RPBA
Rotating Priority Bus Arbitration Select. When RPBA is high, rotating priority for the
ADSP-21368 external bus arbitration is selected. When RPBA is low, fixed priority is
selected. This signal is a system configuration selection which must be set to the same
value on every processor in the system.
1 The pull-up is always enabled on the ADSP-21367 and ADSP-21369 processors. The pull-up on the ADSP-21368 processor is only enabled on the processor with ID2–0 = 00x
2 Pull-up can be enabled/disabled, value of pull-up cannot be programmed.
Table 8. Pin Descriptions (Continued)
Name
Type
State During/
After Reset
(ID = 00x)
Description