28.6.2.7 Sequential Logic

Each LUT pair can be connected to the internal sequential logic, which can be configured to work as D flip flop, JK flip flop, gated D-latch or RS-latch by writing the Sequential Selection bits on the corresponding Sequential Control x register (SEQCTRLx.SEQSEL). Before using sequential logic, the GCLK_CCL clock and optionally each LUT filter or edge detector must be enabled.

Gated D Flip-Flop (DFF)

When the DFF is selected, the D-input is driven by the even LUT output LUT0, and the G-input is driven by the odd LUT output LUT1, as shown in the following figure.

When the even LUT is disabled LUTCTRL0.ENABLE=0, the flip-flop is asynchronously cleared. The reset command (R) is kept enabled for one APB clock cycle. In all other cases, the flip-flop output (OUT) is refreshed on rising edge of the GCLK_CCL, as shown in the following table.

JK Flip-Flop (JK)

When this configuration is selected, the J-input is driven by the even LUT output LUT0, and the K-input is driven by the odd LUT output LUT1, as shown in the following figure.

When the even LUT is disabled LUTCTRL0.ENABLE=0, the flip-flop is asynchronously cleared. The reset command (R) is kept enabled for one APB clock cycle. In all other cases, the flip-flop output (OUT) is refreshed on rising edge of the GCLK_CCL, as shown in the following table.

Gated D-Latch (DLATCH)

When the DLATCH is selected, the D-input is driven by the even LUT output LUT0, and the G-input is driven by the odd LUT output LUT1, as shown in the following figure.

When the even LUT is disabled LUTCTRL0.ENABLE=0, the latch output will be cleared. The G-input is forced enabled for one more APB clock cycle, and the D-input to zero. In all other cases, the latch output (OUT) is refreshed as shown in the following table.

RS Latch (RS)

When this configuration is selected, the S-input is driven by the even LUT output LUT0, and the R-input is driven by the odd LUT output LUT1, as shown in the following figure.

When the even LUT is disabled LUTCTRL0.ENABLE=0, the latch output will be cleared. The R-input is forced enabled for one more APB clock cycle and S-input to zero. In all other cases, the latch output (OUT) is refreshed as shown in the following table.