SLASER3A July 2018 – November 2018 DAC61408 , DAC71408 , DAC81408
PRODUCTION DATA.
A serial interface access cycle is initiated by asserting the CS pin low. The serial clock SCLK can be a continuous or gated clock. SDI data are clocked on SCLK falling edges. A regular serial interface access cycle is 24 bits long with error checking disabled and 32 bits long with error checking enabled, thus the CS pin must stay low for at least 24 or 32 SCLK falling edges. The access cycle ends when the CS pin is de-asserted high. If the access cycle contains less than then minimum clock edges, the communication is ignored. If the access cycle contains more than the minimum clock edges, only the first 24 or 32 bits are used by the device. When CS is high, the SCLK and SDI signals are blocked and the SDO is in a Hi-Z state.
In an error checking disabled access cycle (24 bits long) the first byte input to SDI is the instruction cycle which identifies the request as a read or write command and the 6-bit address to be accessed. The last 16 bits in the cycle form the data cycle.
BIT | FIELD | DESCRIPTION |
---|---|---|
23 | RW | Identifies the communication as a read or write command to the address register. R/W = 0 sets a write operation. R/W = 1 sets a read operation. |
22 | x | Don't care bit. |
21-16 | A[5:0] | Register address. Specifies the register to be accessed during the read or write operation. |
15-0 | DI[15:0] | Data cycle bits. If a write command, the data cycle bits are the values to be written to the register with address A[5:0]. If a read command, the data cycle bits are don't care values. |
Read operations require that the SDO pin is first enabled by setting the SDO-EN bit. A read operation is initiated by issuing a read command access cycle. After the read command, a second access cycle must be issued to get the requested data. Data are clocked out on SDO pin either on the falling edge or rising edge of SCLK according to the FSDO bit.
BIT | FIELD | DESCRIPTION |
---|---|---|
23 | RW | Echo RW from previous access cycle. |
22 | x | Echo bit 22 from previous access cycle. |
21-16 | A[5:0] | Echo address from previous access cycle. |
15-0 | DO[15:0] | Readback data requested on previous access cycle. |