Datasheet
SPI/MICROWIRE-Compatible UART and ±15kV ESD-
Protected RS-232 Transceivers with Internal Capacitors
SPI Interface
The MAX3110E/MAX3111E are compatible with SPI,
QSPI (CPOL = 0, CPHA = 0), and MICROWIRE serial-
interface standards (Figure 2). The MAX3110E/
MAX3111E have a unique full-duplex-only architecture
that expects a 16-bit word for DIN and simultaneously
produces a 16-bit word for DOUT regardless of which
read/write register is used. The DIN stream is moni-
tored for its first two bits to tell the UART the type of
data transfer being executed (see the
Write
Configuration Register
,
Read Configuration Register
,
Write Data Register
, and
Read Data Registe
r sections).
DIN (MOSI) is latched on SCLK’s rising edge. DOUT
(MISO) should be read into the µP on SCLK’s rising
edge. The first bit (bit 15) of DOUT transitions on CS’s
falling edge, and bits 14–0 transition on SCLK’s falling
edge. Figure 3 shows the detailed serial timing specifi-
cations for the synchronous SPI port.
Only 16-bit words are expected. If CS goes high in the
middle of a transmission (any time before the 16th bit),
the sequence is aborted (i.e., data does not get written
to individual registers). Most operations, such as the
clearing of internal registers, are executed only on CS’s
rising edge. Every time CS goes low, a new 16-bit
stream is expected. An example of using the Write
Configuration Register is shown in Figure 4.
Table 1 describes the bits located in the Write Config-
uration, Read Configuration, Write Data, and Read
Data Registers. This table also describes whether the
bit is a read or a write bit and the power-on reset state
(POR) of the bits. Figure 5 shows an example of parity
and word-length control.
CS
SCLK
SCLK
SCLK
SCLK
(CPOL = 0, CPHA = 0)
(CPOL = 0, CPHA = 1)
(CPOL = 1, CPHA = 0)
(CPOL = 1, CPHA = 1)
COMPATIBLE
WITH MAX3110E/MAX3111E
NOT COMPATIBLE
WITH MAX3110E/MAX3111E
DIN
MSB 1314 12 11 10 9 8 7 6 5 4 3 2 1 LSB
DOUT
MSB 1314 12 11 10 9 8 7 6 5 4 3 2 1 LSB
Figure 2. Compatible CPOL and CPHA Timing Modes
• • •
• • •
• • •
• • •
CS
SCLK
DIN
DOUT
t
CSO
t
CSS
t
CL
t
DS
t
DH
t
DV
t
CH
t
DO
t
TR
t
CSH
t
CS1
Figure 3. Detailed Serial Timing Specifications for the Synchronous SPI Port
Maxim Integrated
11
MAX3110E/MAX3111E