  The Giant Radio Array for Neutrino Detection (GRAND) aims to detect the radio
emission from air showers triggered by ultra-high-energy particles in the
atmosphere. GRANDProto300 is its pathfinder array, of which the first 100
detection units have already been produced. A custom data acquisition (DAQ)
board receives, processes, and transmits radio signals. We report on the board
design, and on the functions and performance tests applied to it. Function
tests are of signal acquisition and transmission, and of the field-programmable
gate array (FPGA) filter algorithm. Performance tests are of the
analog-to-digital conversion and GPS time accuracy. We developed an efficient
system to automate the test, in line with the mass-production scale needed to
build future, larger versions of GRAND.
