Journal ArticleDesign, construction, and testing of the APOLLO ATCA blades for use at the HL-LHCAkpinar, Alp; Blaizot, Aymeric; Cholak, Serhii; de_Castro, Gianfranco; Demiragli, Zeynep; Duquette, Alec; Fulcher, J (ORCID:000000022801520X); Gastler, Dan; Hahn, Kristian; Hazen, Eric Shearer; Jeon, Si Hyun; Kotamnives, Peace; Madorsky, Alexander; Monk, David; Noorudhin, Sheena; Oshiro, Michael; Rohlf, James; Strohman, Charles Ralph; Tsai, Emily Minyun; Wittich, Peter; Yuan, Siqi; Zou, Ruithe_CMS_collaboration<title>Abstract</title> <p>The Apollo Advanced Telecommunications Computing Architecture (ATCA) platform is an open-source design consisting of a generic “Service Module” (SM) and a customizable “Command Module” (CM), allowing for cost-effective use in applications such as the readout of the inner tracker and the Level-1 track trigger for the CMS Phase-II upgrade at the HL-LHC. The SM integrates an intelligent IPMC, robust power entry and conditioning systems, a powerful system-on-module computer, and flexible clock and communication infrastructure. The CM is designed around two Xilinx Ultrascale+ FPGAs and high-density, high-bandwidth optical transceivers capable of 25 Gb/s. Crates of Apollo blades are currently being tested at Boston University, Cornell University, and CERN.</p>JINST 20 (2025) 04, C040012025-04-0110678176Journal of Instrumentation2004C040011748-0221https://doi.org/10.1088/1748-0221/20/04/C040012046626National Science Foundation