________________________________________________________________
Maxim Integrated Products
17
MAX9264 Evaluation Kit
Evaluates: MAX9263/MAX9264
Detailed Description of Hardware
The MAX9264 EV kit provides a proven layout for the
MAX9264 GMSL deserializer with HDCP. On-board level
translators, S/PDIF-to-I
2
S audio, and easy-to-use USB-
PC connection are included on the EV kit.
The MAX9264 EV kit board layout is divided into four
principal sections.
From header H1 to connector J1 are the support compo-
nents specific to the MAX9264. On-board LDO regulator
U2 powers the AVDD, DVDD, and IOVDD supplies from
VIN. Jumper JU9 optionally connects VIN to the link
cable, powering the remote EV kit board.
Below header H1, the board layout has three sections:
microcontroller (U10–U14), I
2
C slave device (U15), and
audio converter circuits (U20–U25). The microcontroller
and I
2
C slave device sections are identical on the
MAX9263 and MAX9264 EV kits.
The audio section of the MAX9263 EV kit contains
S/PDIF-to-I
2
S-audio-converter circuits (U20–U25), which
can be disabled by JU210 for applications already
having I
2
S audio.
The audio section of the MAX9264 EV kit contains I
2
S-
to-audio DAC circuits (U20, U21) and a Class D stereo
power amplifier (U25). The audio DAC circuit is similar to
the MAX9850 EV kit, and the power amplifier (PA) circuit
is similar to the MAX9701 EV kit.
The MAX9264 EV kit optionally supports a
MAX94 phase-locked loop (U29).
User-Supplied Interface
To use the MAX9264 EV kit with a user-supplied inter-
face, first cut the PCB traces at JU141 and JU142.
Next, apply your own TX/SCL signal at the U1 side of
JU141 and RX/SDA at the U1 side of JU142. Refer to
the MAX9263/MAX9264 IC data sheet for details about
UART protocol for base mode, write data format, read
data format, selecting base mode or bypass mode, and
selecting a UART or I
2
C slave device.
User-Supplied Power Supply
The MAX9263 and MAX9264 EV kits are powered com-
pletely from the USB port by default. The 5V USB bus
power is supplied to the remote EV kit over the link cable
by default. Jumper JU10 powers the link cable VBUS
from the 5V USB supply, and jumper JU9 connects the
link cable VBUS to the VIN power supply.
To provide external power to each EV kit’s VIN, and still
power both microcontrollers from the USB, remove the
shunt from JU9 but leave the shunt at JU10 installed. The
link cable carries the USB 5V bus power to the remote
EV kit board, but external user-supplied VIN supplies are
required to power the MAX9263 and the MAX9264.
To provide different power supplies to DVDD, AVDD, and
IOVDD, remove the shunts from JU21, JU22, and JU23
and apply external user-supplied power at the DVDD,
AVDD, and IOVDD oval pads.
The I
2
S audio link demonstration requires both MAX9263
EV kit and MAX9264 EV kit microcontrollers (U12) to be
powered; otherwise, the on-board S/PDIF-to-I
2
S con-
verter or the I
2
S audio DAC are not initialized.
Detailed Description of Firmware
The DS89C450 microcontroller (U12) runs custom firm-
ware that ensures that no breaks occur within register
read/write commands. The firmware records 9-bit even-
parity data received from the USB interface while RTS is
set, and plays back the 9-bit data with 1.5 stop bits timing
when RTS is cleared. Data received from the MAX9264 is
immediately relayed to the USB.
The audio chips are initialized by an I
2
C command
sequence sent by the firmware when the microcontroller
is reset. This initialization sequence covers both the
S/PDIF-to-I
2
S converter and the MAX9850 I
2
S stereo
audio DAC. Pressing SW122 resets the microcontroller,
resending the audio I
2
C initialization commands.
The firmware also supports a small set of commands,
available when RTS is clear. Since all register read/
write requests are sent with RTS set, there is no conflict
between register data and firmware commands. These
firmware commands are issued automatically by the
MAX9264 EV kit software GUI. The following information
is provided for reference only:
•
Firmware command “?” prints the firmware version
banner message and brief command list.
•
Firmware command “B” changes the baud rate by
changing the internal TH1 baud-rate divisor. Refer
to firmware help command “?” for details. Pressing
SW122 resets the USB baud rate to 921600 baud.
The software GUI automatically sends the baud-rate
change command.
•
Firmware command “T” supports waking up the
MAX9263 from the MAX9264 side of the link.
Command “T” performs a dummy read, followed by a
delay on the order of 1ms to 8ms, and finally writes a
register value. For example, send “T810504800483”
to read from device address 0x81 register 0x05,
delay 4ms, then write to device address 0x80
register 0x04 data 0x83. This is the MAX9263 wake-
up sequence for the default device addresses. The
software GUI automatically sends this command
when the
Wake Up MAX9263
button is pressed.
•
Firmware commands “R” and “W” read and write
device registers. The 8-bit device address, register
address, length, and data are sent in hexadecimal.
