Introduction
496
SLAU367P – October 2012 – Revised April 2020
Copyright © 2012–2020, Texas Instruments Incorporated
Sequencer for Acquisition, Programmable Pulse Generator, and Physical
Interface (SAPH, SAPH_A)
21.1 Introduction
The sequencer for acquisition, programmable pulse generator, and physical interface (SAPH or SAPH_A)
is one of the submodules in the Ultrasonic Sensing Solution (USS or USS_A) module. The USS module is
designed for analog-to-digital converter (ADC) based ultrasonic sensing technology in various
measurement applications. See
for details.
The SAPH module features the PPG generator, and the SAPH_A module features the PPG_A generator.
The SAPH_A is a superset of SAPH; therefore, SAPH_A is specifically named only when necessary to
distinguish from the SAPH module.
The SAPH or SAPH_A consist of three blocks (see
•
Acquisition Sequencer (ASQ)
•
Programmable Pulse Generator (PPG or PPG_A)
•
Physical Interface (PHY)
SAPH_A provides additional bias voltages for optional external signal conditioning like low-noise amplifiers
(LNAs) and booster amplifiers.
•
PPG or PPG_A block: Generates pulses at different frequencies.
•
PHY block: Controls output channels and input channels of the USS module.
•
ASQ block: The entire measurement sequence can be controlled by user software (called register
mode) or by ASQ without any CPU intervention (called auto mode). The auto mode helps reduce the
measurement power consumption, because the CPU can stay in LPM0 during measurement.
•
External bias generator on SAPH_A
NOTE:
Naming convention for register names and bit fields:
•
SAPH registers: RegisterName or RegisterName.BitField
•
Other module registers: ModuleNameRegisterName or
ModuleNameRegisterName.BitField
•
Code written for USS and SAPH modules is also accepted by USS_A and SAPH_A
modules. The register names are resolved automatically.
NOTE:
Before writing to any SAPH register with an offset address greater than 0x0F, unlock the
registers by writing 0x45B to the KEY register. The unlock must be performed only once.
Writing any other value to the KEY register locks the registers. Read accesses are always
allowed.