LDS - Load Data from Data Space Using Direct Addressing

The LDS instruction is used to load data form the bus matrix and into the serial shift register for serial read out. The LDS instruction is based on direct addressing, and the address must be given as an operand to the instruction for the data transfer to start. Maximum supported size for address and data is 16 bit. LDS supports repeated memory access when combined with the REPEAT instruction.

As shown in Figure 1, after issuing the SYNCH character followed by the LDS instruction, the number of desired address bytes, as indicated by the SizeA field in the instruction, must be transmitted. The output data size is selected by the SizeB field, and is issued after the specified Guard Time. When combined with the REPEAT instruction, the address must be sent in for each iteration of the repeat, meaning after each time the output data sampling is done. There is no automatic address increment when using REPEAT with LDS, as it uses a direct addressing protocol.

Figure 1. LDS Instruction Operation