Control A

Name:
CTRLA
Offset:
0x00
Reset:
0x00
Access:
-
Bit76543210
SDASETUPSDAHOLD[1:0]FMPEN
AccessR/WR/WR/WR/W
Reset0000

Bit 4 – SDASETUP: SDA Setup Time

SDA Setup Time

By default, there are four clock cycles of setup time on SDA out signal while reading from the slave part of the TWI module. Writing this bit to ‘1’ will change the setup time to eight clocks.

ValueNameDescription
0 4CYC SDA setup time is four clock cycles
1 8CYC SDA setup time is eight clock cycle

Bits 3:2 – SDAHOLD[1:0]: SDA Hold Time

SDA Hold Time

Writing these bits selects the SDA hold time.

Table 1. SDA Hold Time
SDAHOLD[1:0] Nominal Hold Time Hold Time Range Across All Corners in ns Description
0x0 OFF 0 Hold time OFF.
0x1 50 ns 36 - 131 Backward compatible setting.
0x2 300 ns 180 - 630 Meets SMBus specification under typical conditions.
0x3 500 ns 300 - 1050 Meets SMBus specification across all corners.

Bit 1 – FMPEN: FM Plus Enable

FM Plus Enable

Writing these bits selects the 1 MHz bus speed (Fast mode plus, Fm+) for the TWI in default configuration.

ValueDescription
0 Fm+ disabled
1 Fm+ enabled