35.5.1 I/O Lines

To use the SERCOM’s I/O lines, the I/O pins must be configured as direct using the System Configuration registers. (See System Configuration and Register Locking (CFG) from Related Links.) I²C does not operate through PPS. (See the DEVCFG1 configuration bits SCOM_HSEN[x] in Configuration Bits Fuses and also the CFGCON1 SCOMn_HSEN in CFGCON1(L) register.)

Note:

SERCOM6 has only I²C functionality and, therefore, the direct configuration using System Configuration register is not required.

SERCOM Instances.

Table 35-2. SERCOM Peripheral Feature Table
SERCOM	FIFO Depth	SPI	USART	I2C/SMBus	1.8V I2C/SMBus	Full Speed	48-Pin	132-Pin
SERCOM0 (through PPS)	4	Yes	Yes	—	—	—	Yes	Yes
SERCOM0 (fixed pins)	4	Yes	Yes	Yes	—	Yes	Yes	Yes
SERCOM1 (through PPS)	2	Yes	Yes	—	—	—	Yes	Yes
SERCOM1 (fixed pins)	2	Yes	Yes	Yes	—	Yes	Yes	Yes
SERCOM2 (through PPS)	2	Yes	Yes	—	—	—	Yes	Yes
SERCOM2 (fixed pins)	2	Yes	Yes	Yes	Yes⁽¹⁾	Yes	—	Yes
SERCOM3 (through PPS)	2	Yes	Yes	—	—	—	Yes	Yes
SERCOM4 (through PPS)	2	Yes	Yes	—	—	—	—	Yes
SERCOM5 (through PPS)	2	Yes	Yes	—	—	—	—	Yes
SERCOM6 (fixed pins)	2	—	—	Yes	—	—	Yes	Yes
Note: When used with external (off-chip) 1.8V pull-ups.

When the SERCOM is used in I²C mode, the SERCOM controls the direction and value of the I/O pins. In I²C mode, pull-up resistors are disabled. External pull-up resistors are required for proper function.