8.5.2.10 Sending Multi-Byte Commands

The ADS1291, ADS1292, and ADS1292R serial interface decodes commands in bytes and requires 4 t_CLK cycles to decode and execute. Therefore, when sending multi-byte commands, a 4 t_CLK period must separate the end of one byte (or opcode) and the next.

Assume CLK is 512 kHz, then t_SDECODE (4 t_CLK) is 7.8125 µs. When SCLK is 16 MHz, one byte can be transferred in 500 ns. This byte-transfer time does not meet the t_SDECODE specification; therefore, a delay must be inserted so the end of the second byte arrives 7.3125 µs later. If SCLK is 1 MHz, one byte is transferred in 8 µs. Because this transfer time exceeds the t_SDECODE specification, the processor can send subsequent bytes without delay. In this later scenario, the serial port can be programmed to move from single-byte transfer per cycle to multiple bytes.