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 4 clock cycles of setup time on SDA out signal while reading from slave part of the TWI module. Writing this bit to '1' will change the setup time to 8 clocks.

ValueNameDescription
0 4CYC SDA setup time is 4 clock cycles
1 8CYC SDA setup time is 8 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 (ns) Description
0x0 OFF 0 Hold time off.
0x1 50ns 36 - 131 Backward compatible setting.
0x2 300ns 180 - 630 Meets SMBus specification under typical conditions.
0x3 500ns 300 - 1050 Meets SMBus specification across all corners.

Bit 1 – FMPEN: FM Plus Enable

FM Plus Enable

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

ValueDescription
0 Fm+ disabled
1 Fm+ enabled