Cirrus Logic CDB5480U - Manual (Page 9)

CDB5480U
DS893DB5 9
1.4.2 Interface to Microcontroller
Interface headers J17 and J19 are provided to allow the CDB5480U to be connected to an external energy
registration device or an external microcontroller. Interface header J17 provides direct access to the
CS5480 pins while interface header J19 provides an isolated connection. It is imperative to use the
isolated 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 9 for details on signal
isolation.
Interface header J19 can be used to connect to the external microcontroller. To connect the CS5480 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
isolators. 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 jumper (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.
1.4.4 Additional Device Pin Access
The CS5480’s digital output pins DO1, DO2, and DO3 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 CS5480 system clock can be connected to an onboard quartz crystal or an external clock can be
supplied to the CS5480 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.