  We make use of the S=1 pseudospin formalism to describe the charge degree of
freedom in a model high-$T_c$ cuprate with the on-site Hilbert space reduced to
the three effective valence centers, nominally Cu$^{1+,\,2+,\,3+}$. Starting
with a parent cuprate as an analogue of the quantum paramagnet ground state and
using the Schwinger boson technique we found the pseudospin spectrum and
conditions for the pseudomagnon condensation with phase transition to a
superconducting state.
