Datasheet

78M6610+PSU Data Sheet
4 Serial Interfaces
All user registers are contained in a 256 word (24-bits each) area of the on-chip RAM and can be
accessed through the UART, SPI, or I
2
C interfaces. For word-addressable SPI and I
2
C interfaces, one
must divide the documented register address by 3. While access to a single byte is possible with some
interfaces, it is highly recommended that the user access words (or multiple words) of data with each
transaction.
Serial Interface Selection
The 78M6610+PSU provides UART, I
2
C, and SPI interface options, but only one interface can be active
at a time. The user activates the interface through the configuration of pins IFCONFIG and SSB/DIR/SCL
according to the following table.
Selected Interface
SSB/DIR/SCL
IFCONFIG
SPI X (don’t care) 0
UART 0 1
I
2
C 1 1
The interface selection pins are sampled following power-on and reset. The user should allow at least
10ms from a power-on or reset event for them to be latched and the serial interface selected. During this
time the status of these pins must not change.
Warning
Where applicable, pins should be configured via pull-up and pull-down resistors as these
pins could become outputs after initialization. Therefore, direct connection to GNDD/GNDA
or V
3P3D
/V
3P3A
supplies must be avoided.
Device Address (UART)
The UART interface supports a multi-point communications protocol. Each device is identified by a
specific address that is configured through the DevAddr register and pins Addr0 and Addr1 according to
the following figure. DevAddr Register Bits 23 through 7 are not used and should be set to 0. Their status
has no effect on the device address.
7 6
5 4 3
2 1 0
DevAddr Register bit 5:0
ADDR1 Pin
SPCK/ADDR0 Pin
Device Address (24-pin Package)
7 6
5 4
3 2 1 0
DevAddr Register bit 6:0
SPCK/ADDR0 Pin
Device Address (16-pin Package)
A change of the address is always effective after a power-on or reset. During the initialization following a
power-on or reset, the DevAddr register value is restored with the value contained in Flash memory and
the address pin status is acquired.
It is possible to modify the device address by setting the DevAddr register (through any of the interfaces)
as well as the address pins status. If DevAddr register is modified, it is necessary to save its content into
Flash through the ACC command. Following a reset or power-on the device will resume operation with
the new address.
Rev 3 41