MCP3919 Datasheet, PDF (46/88 Pages) Microchip Technology – 3V Three-Channel Analog Front End

MCP3919
6.5 Continuous Communications,
Looping on Register Sets
The MCP3919 digital interface can process communi-
cations in Continuous mode without having to enter an
SPI command between each read or write to a register.
This feature allows the user to reduce communication
overhead to the strict minimum, which diminishes EMI
emissions and reduces switching noise in the system.
The registers can be grouped into multiple sets for con-
tinuous communications. The grouping of the registers
in the different sets is defined by the READ<1:0> and
WRITE bits that control the internal SPI communication
address pointer. For a graphical representation of the
register map sets in function of the READ<1:0> and
WRITE bits, see Table 9-2.
In the case of a continuous communication, there is
only one control byte on SDI to start the communication
after a CS pin falling edge. The part stays within the
same communication loop until the CS pin returns logic
high. The SPI internal register address pointer starts by
transmitting/receiving the address defined in the con-
trol byte. After this first transmission/reception, the SPI
internal register address pointer automatically incre-
ments to the next available address in the register set
for each transmission/reception. When it reaches the
last address of the set, the communication sequence is
finished. The address pointer automatically loops back
to the first address of the defined set and restarts a new
sequence with auto-increment (see Table 6-6). This
internal address pointer automatic selection allows the
following functionality:
• Read one ADC channel data, pairs of ADC
channels or all ADC channels continuously
• Continuously read the entire register map
• Continuously read or write each separate register
• Continuously read or write all configuration
registers
CS
SCK
8x
24x
24x
...
24x
24x
24x
...
24x
SDI
SDO
Don’t care
CONTROL
BYTE
Starts read sequence
at address ADDR
Hi-Z
ADDR
ADDR + 1
...
Complete READ sequence
Don’t care
ADDR + n
ADDR
ADDR + 1
...
Complete READ sequence
Continuous READ communication (24-bit format)
ADDR + n
ADDRESS SET
ADDR
ADDR + 1
...
ADDR + n
Complete
READ
sequence
Roll-over
CS
SCK
8x
24x
24x
...
24x
24x
24x
...
24x
SDI
SDO
Don’t care
CONTROL
BYTE
Starts write sequence
at address ADDR
ADDR
ADDR + 1
...
ADDR + n
Complete WRITE sequence
Hi-Z
ADDR
ADDR + 1
...
Complete WRITE sequence
ADDR + n
ADDRESS SET
ADDR
ADDR + 1
...
ADDR + n
Complete
WRITE
sequence
Roll-over
FIGURE 6-6:
Continuous WRITE communication (24-bit format)
Continuous Communication Sequences.
DS20005347A-page 46
 2014 Microchip Technology Inc.