The output bit mapper allows to change the output bit order for any selected interface mode.

It is a two step process to change the output bit mapping and assemble the output data bus:

1. In parallel interface mode, the maximum output resolution is 18-bit, in serial interface mode the maximum output resolution is 20-bit. Each output bit of either channel has a unique identifier bit as shown in the Table 8-10. The MSB starts with bit D19 – depending on output resolution chosen the LSB would be D6 (14-bit) to D0 (20-bit). The ‘previous sample’ is only needed in 2-w mode.
2. The bit mapper is then used to assemble the output sample. The following sections detail how to remap both a parallel and a serial output format.

In parallel SDR mode, a data bit (with unique identifier) needs to be assigned to each output pin using the register addresses as shown in Figure 8-43. The example on the right shows the 14-bit output data bus remapped to reverse order to where the MSB starts on pin D2 instead of pin D15.

In parallel DDR mode, a data bit (with unique identifier) needs to be assigned to each output pin for both the rising and the falling edge of the DCLK using the register addresses as shown on the left of Figure 8-44. D9 and D10 are used for 16 and 18-bit output. The example on the right shows the 14-bit output data bus remapped to where the MSB starts on D17 instead of D11.

In the serial output mode, a data bit (with unique identifier) needs to be assigned to each location within the serial output stream. There are a total of 40 addresses (0x39 to 0x60). When using complex decimation, the output bit mapper is applied to both the “I” and the “Q” sample.

2-wire mode: in this mode both the current and the previous sample have to be used in the address space as shown in Figure 8-45 below. The address order is different for 14/18-bit and 16/20-bit. Note: there are unused addresses between samples for resolution less than 20-bit (grey back ground), which can be skipped if not used.

In the following example (Figure 8-46), the 16-bit 2-wire serial output is reordered to where pin D12 carries the 8 MSB and pin D11 carries 8 LSBs.

1-wire mode: Only the ‘current’ sample needs to programmed in the address space.