Cirrus Logic CDB5484U - Manual (Page 10)

CDB5484U
10 DS919DB5
1.4.2 Interface to Microcontroller
Interface headers J17 and J19 are provided to allow the CDB5484U to be connected to an external energy
registration device or an external microcontroller. Interface header J17 provides direct access to the
CS5484 pins while interface header J19 provides an isolated connection. It is imperative to use the iso-
lated connection (J19) when high-voltage signals are used. Failure to use isolation can result in damage
to components or electrical shock. Refer to “Digital Isolation” on page 10 for details on signal isolation.
Interface header J19 can be used to connect to the external microcontroller. To connect the CS5484 to
an external microcontroller, R34, R35, R36, R37, R38, R39, R40, R41, R42, and R43 must be removed
from the board.
1.4.3 Digital Isolation
Two types of isolation are provided, including a low-speed optical coupler for UART-only and high-speed
digital isolation for UART and SPI communication. Default jumper settings provide high-speed digital iso-
lators. To enable high-speed digital isolators, place jumpers (J18 and J20) in the RX to DIGITAL position
and TX to DIGITAL position. To enable the high-speed digital isolators, it is also necessary to install jump-
er (J50) in the VDDA position. To enable low-speed optical UART communication, place jumpers (J18 and
J20) in the RX to OPTICAL position and TX to OPTICAL position.
The high-speed digital isolators operate from DC to 150Mbps. The low-speed optical couplers operate to
a maximum speed of about 4.8kHz. All the signals supplied to the isolators are available to the MCU ex-
cept CPUCLK.
1.4.4 Additional Device Pin Access
The CS5484’s digital output pins (DO1, DO2, DO3, and DO4) are routed to LEDs, which provide a simple
visual check of the digital output. Jumpers J39, J40, J41, and J42 are equipped at the factory with jumpers
to enable the LEDs. The DO1 digital output pin is supplied to the digital isolation using jumper J49.
The MODE pin jumper (J15) should be installed in the VDDA to MODE position.
The CS5484 system clock can be connected to an onboard quartz crystal, or an external clock can be
supplied to the CS5484 XIN pin though jumper J48. To connect the onboard quartz crystal, install jumper
J43 in the XIN to CRYSTAL position. To connect XIN to an external clock, install jumper J43 in the XIN to
XIN_EXT position.