On-Chip Codec (7 Pins) - Motorola DSP56156 Manual

debug mode due to an external debug request (DR), an internal software debug
request (DEBUG), a hardware breakpoint occurrence or a trace/step occur-
rence, this line will be asserted for three T cycles to indicate that the chip has
entered the debug mode and is waiting for commands. Data is always shifted
out the OnCE serial port most significant bit (MSB) first.
(Debug Request Input) - The debug request input provides a means of entering
DR
the debug mode of operation. This pin when asserted (negative true logic) will
cause the DSP to finish the current instruction being executed, enter the debug
mode, and wait for commands to be entered from the debug serial input line.
2.10

ON-CHIP CODEC (7 PINS)

AUX (Auxiliary input) - This pin is selected as the analog input to the A/D converter
when the INS bit is set in the codec control register COCR. This pin should be
left floating when the codec is not used.
BIAS (Bias current pin) - This input is used to determine the bias current for the analog
circuitry. Connecting a resistor between BIAS and VGNDA will program the cur-
rent bias generator. This pin should be left floating when the codec is not used.
MIC (Microphone input) - This pin is selected as the analog input to the A/D con-
verter when the INS bit is cleared in the codec control register COCR. This pin
should be left floating when the codec is not used.
SPKP (Speaker Positive Output) - This pin is the positive analog output from the on-
chip D/A converter. This pin should be left floating when the codec is not used.
SPKM (Speaker Negative Output) - This pin is the negative analog output from the on-
chip D/A converter. This pin should be left floating when the codec is not used.
VREF (Voltage Reference Output) - This pin is the op-amp buffer output in the ref-
erence voltage generator. It has a value of (2/5) VDDA. This pin should always
be connected to the ground through two capacitors (typically a 0.1 µ f ceramic
in parallel with a 15 µ f tantalum), even when the codec is not used.
VDIV (Voltage Division Output) - This output pin is also the input to the on-chip op-
amp buffer in the reference voltage generator. The pin is connected to a resistor
divider network located within the codec block which provides a voltage equal
to (2/5)VDDA. This pin should be connected to the ground via a capacitor when
the codec is used and should be left floating when the codec is not used.
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ON-CHIP CODEC (7 PINS)
DSP56156 PIN DESCRIPTIONS MOTOROLA