JEM-EUSO [1] is intended to be a space-borne fruorescence te lescope onboard of JEM/EF (Japanese Experimental Modeul/Exposure Facility) on the International Space Station (ISS). The main goal of the JEM-EUSO project is to detect the Extensive A ir Showers (EAS) produced by the Extreme Energy Cosmic Rays (EECRs) with energies above 1 0 19 eV from the extragalactic objects. As a pathfinder, the JEM-EUSO collaboration is curr ently developing a balloon-borne fluorescence telescope experiment, called EUSO-Balloon, f unded by CNES, the French space agency. It will perform end-to-end tests of the JEM-EUSO sub systems and instrumental concept, and measure the UV background for space-based EECR detector s. It involves several French in- stitutes (LAL, APC and IRAP) as well as several key institute s of the JEM-EUSO collaboration. The EUSO-Balloon instrument consists of an UV telescope and an infrared camera. The UV telescope will be operated at an altitude of 40 km to observe t he background and possibly signal photons in the fluorescence UV range (290-430 nm), which are e mitted along shower tracks gen- erated by ultra high energy cosmic rays with energies above 1 0 18 eV interacting with the earth’s atmosphere. The balloon experiment will be equipped with el ectronics and acquisition systems, as close as possible to the ones designed for the UV telescope of main JEM-EUSO instrument. The past years have been devoted to the design, the fabricati on and the tests of the prototype boards of the PDM, of the digital processor, and the flight mod els of optics, electronics and the IR camera for EUSO-Balloon. Here we focus on the PDM, the core element of the JEM-EUSO foca l surface. We first describe all key items of the PDM, from the photodetectors to the FPGA b oard, the first stage of the data processing (DP). We then report on the tests carried out on th e integration to assess their func- tionality and their suitability for a balloon mission.