Cirrus Logic CRD48L10 - Manual (Page 37)

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10.1 External Control of CS48L10
Chapter 10
External Control of CRD48L10-4in4out
External control of the CRD48L10 can be viewed as two different components:
• External Control of CS48L10 DSP
• External Control of CRD48L10-4in4out Audio Subsystem
Some evaluations of the CS48L10 using an external controller may require only configuration of the DSP while using the
built-in audio paths of the CRD48L10-4in4out. For this reason, we have split external control options into two parts. The
customer can choose to configure the audio paths of the board as described in
Chapter 3 and then control the DSP
externally.
The user also has the option to configure any of the components on the I 2 C bus of the CRD48L10. This gives the user
flexibility to define different audio paths than the defaults programmed into the local MCU.
10.1 External Control of CS48L10
The CS48L10 is configured via its SPI port and the INT/BSY/RESET pins. The control interface for the CS48L10 is
released by the on-board MCU when pin 9 of TP15 is pulled low. This is handled by the CDB-MCU-DEBUG automatically
when plugging into JP2 and using the Cirrus tools.
In order to use an external MCU to configure the DSP, short together pins 9 and 10 of TP15. This can be accomplished
with a 2-pin shunt, or it can be built into a cable harness.
The interface voltage level on TP15 and JP3 is controlled by the +VPROBE voltage rail. By default, the board is configured
for +1.8 V on the interface, but this can be changed to +3.3 V by moving the shunt on jumper J15. If a voltage other than
+1.8 V or +3.3 V is desired, the U13 regulator can be reconfigured to provide a different voltage. The schematic of the
CRD48L10-4in4out shows a configuration table next to U13 explaining how to generate +2.5 V, +2.7 V, +3.0 V.
10.2 External Control of CRD48L10-4in4out Board
The other components on the CRD48L10 that can be configured are the CS42L73, CS8416, CS8406, and on-board
oscillator. The oscillator is enabled/disabled via a GPIO from the on-board MCU. The rest of the board is configured using
an I
2 C bus. Section 3.2.6 explains how to configure the I 2 C bus for external control mode. Section 3.2.5 explains how to
disable the on-board oscillator via the LCD menu.
Table 10-1. DSP External Control Signals
Header Voltage Signals
JP3 +VPROBE SPI Bus
TP15 +VPROBE Dongle_Active*—DSP Control Tri-state
TP15 +VPROBE DSP_RESET*, DSP_INT*, DSP_BSY*
Table 10-2. Other CRD48L10-4in4out Board Control Signals
Header Voltage Signals
JP3 +VPROBE I 2 C Bus (EXT_SCL, EXT_SDA)
TP4 +1.8 V – +5 V System CLKIN
TP30 +1.8 V Oscillator bypass. Install shunt only when Y1 is disabled.