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rogating the USB socket and insertion of a clean USB stick containing only the system rmware will
initiate a complete recovery automatically.
IC164 is a MiniLogic ML61C282PR precision voltage detector, with a threshold of 2.8V, built in hysteresis
and a CMOS output, used to reset IC162 at power on.
IC163 is an Intersil USB switch, type ISL54220, which routes the USB socket on the rear panel either to
the Venice 6.2 module, for normal audio applications, or to IC162 when the system SW is being up-
graded from a USB stick. Note that it is positioned underneath the Venice 6.2 module, close to the USB
socket.
The USB high side power switch IC168 is close to IC163. It is a Richtek RT9702A fed from the main +5V
power supply. It is rated at 1.1 amps output and can ag up a fault condition on the USB bus from pin 3;
this is routed to IC162.
The Frontier Silicon Venice 6.2WB module is plugged into the input board via a 64 way connec-
tor CN62. This WB version of the module supports Band 3 DAB/DAB+ digital radio for use in Europe,
Australia, Canada, Korea and other Digital Radio markets. It also supports USB2, and Ethernet up to 100
Mb/s, enabling the AVR400 to be a network audio client. A spare copy of the AVR400’s unique MAC
(Media Access Controller) address can be found on the screening can of the Venice 6.2 module. Its FM
radio function is not used.
The Venice 6.2 is operated in slave mode via the UART pins 9 and 10 on CN62. These connect to the sub
micro IC154. The USB I/O signal pins are 11 and 12, routed to the USB switch IC163. The other USB pins
are not used. Pins 26, 27, 28 and 29 make up an SPI bus to work with the Ethernet PHY IC161 (pin 33
receives interrupts from IC161).
Audio is decoded inside the Venice 6 (i.e. from AAC, FLAC, MP3, WMA or WAV) and sent out by two
routes. Pin 32 carries an SPDIF signal (at 48ks/s) for the main system and pins 64 and 63 carry L/R linear
audio for zone 2 to the volume control IC101.
The Venice 6.2 requires +3V3 at up to 300mA average and +1V2 at 200mA average for the core of its
main processor. 3V3 is provided from the main +5V supply via the three terminal regulator IC165 – this
also provides the soft start signal to pin 2 of the 1V2 regulator IC167 (also fed from +5V with some volt-
age drop provided by diodes D803/4). Both regulators are SM types, positioned underneath the Venice
6.2 module.
IC161 is a Micrel KSZ8851 single port Fast Ethernet MAC/PHY controller with an SPI interface. It has a
12KB receive bμFfer and a 6KB transmit bμFfer. It has its own 25MHz crystal oscillator X777. Its 4 I/Osgo
to the Ethernet socket JK52 on the back panel. Its +3V3 power rail is derived from the board’s +5V
supply via the three terminal regulator IC166.
AVR400 RS232 board
This is a daughter board connected to the Input Board via an 18 way plug and socket BN71. The circuitry
is shown on page 14 of the schematic diagram.
It contains two 9 way D-type board mounted plugs JK71 and JK72. JK71 is for RS232 control of the
AVR400. JK72 is used to control an iPod or iPhone via an Arcam rDock or rLead (the latter also supports
iPads).
The RS232 dual transmitter and receiver IC73 is an ST3232 run from the standby +5V supply via D721/
R727 and a series pnp transistor Q722 in common emitter mode referred to the +12V rail. Q721 provides