JAJSVE5 September 2024 DDS39RF12 , DDS39RFS12
PRODUCTION DATA
The FR interface provides fast write-only access to configure NCO frequencies and synchronization. The FR interface is similar to the SPI interface, but 4 bits are sent per clock cycle. The FR timing diagram is shown in Figure 7-60. It uses a R/W bit (always Write for this device), a transaction sync bit (FRS), and 14-bits of address followed by some number of data bytes. The address is decremented after each data byte (consistent with little-endian). The interface is byte addressable and data is committed after each byte. The FR interface is takes 4-bits (one nibble) per clock. For multi-nibble fields, data is sent most-significant nibble first. When the transaction sync bit (FRS) is set, the synchronization event specified in the NCO_SYNC_SRC register field occurs at the rising edge of FRCS. Transactions ended before the completion of the first data byte may not trigger the sync event.
The FR interface registers are listed in Table 7-31. There are two registers that can change the NCO frequency - FR_FREQL[3:0] is 64-bits for each NCO and changes the entire frequency word. FR_FREQS[3:0] is 32-bits for each NCO and changes only the upper 32-bits of the frequency word, providing for faster frequency changes.
Address | Name | Description |
---|---|---|
0x00FF | FR_NCO_AR | FR NCO Accumulator Reset (default: 0x0f) [7:4] RESERVED [3:0] FR_NCO_AR For each bit FR_NCO_AR[n], if set, the accumulator for NCOn is reset on every sync event specified by NCO_SYNC_SRC. Note: This register has no effect when FR_EN=0. |
0x0100-0x011F | FR_FREQL[3:0] | FR 64-bit Frequency for NCO Accumulator (default for FR_FREQL[n]=0x00) The frequency setting for FR_FREQL[0] is at the lowest address. [63:0] FR_FREQL[n] This register is used instead of FREQ[n] when FR_EN=1. Changes to the upper 32-bits of this register also change FR_FREQS[n]. Note: Changes to this register do not take effect until the next sync event specified by NCO_SYNC_SRC. Note: This register has no effect when FR_EN=0. |
0x0120-0x0127 | FR_PHASE[3:0] | FR Phase for NCO Accumulator (default for FR_PHASE[n]=0x0000) The phase setting for FR_PHASE[0] is at the lowest address. [15:0] FR_PHASE[n] This register is used instead of PHASE[n] when FR_EN=1. Note: Changes to this register do not take effect until the next sync event specified by NCO_SYNC_SRC. Note: This register has no effect when FR_EN=0. |
0x0128-0x0137 | FR_FREQS[3:0] | FR 32-bit Frequency for NCO Accumulator (default for FR_FREQS[n]=0x00) The frequency setting for FR_FREQS[0] is at the lowest address. [31:0] FR_FREQS[n] This register is used instead of FREQ[n] when FR_EN=1. Changes to this register also change the upper 32-bits of FR_FREQL[n]. This register only controls the upper 32-bits of the frequency. The lower 32-bits of the frequency are always controlled by FR_FREQL[n]. Note: Changes to this register do not take effect until the next sync event specified by NCO_SYNC_SRC. Note: This register has no effect when FR_EN=0. |