{"id":"7eef4373-3288-4303-ac14-aa09facfcd07","task":"Implement MDB peripheral communication basics to integrate a cashless payment device with a vending machine controller (VMC).","domain":"mdbprotocol.com","steps":["Wire the cashless device onto the MDB serial bus (a multi-drop bus running at a fixed 9600 baud) alongside the coin changer and bill validator.","Address peripherals using MDB's fixed address scheme (e.g., Bill Validator = 30H, Cashless Device #1 = 10H, Cashless Device #2 = 60H).","Distinguish ADDRESS bytes from DATA bytes using the MDB mode bit (set = ADDRESS, clear = DATA) in each transmitted byte.","Respond to periodic VMC POLL commands with any pending status/event data for the device.","Validate each block using the MDB checksum (CHK) byte, computed by adding the ADDRESS byte and all DATA bytes.","Handle the device non-response timeout correctly so the VMC does not falsely mark the peripheral offline."],"gotchas":["MDB was designed cash-first; cashless payment support (session/revalue commands) was added later, so not all VMC firmware or peripheral revisions support the same cashless feature level — feature-level mismatches are a common source of 'payment accepted but not applied' bugs.","Two cashless device addresses exist (Cashless Device #1 at 10H and #2 at 60H, added in a later spec revision) — a VMC or peripheral written against an older single-cashless-device assumption may ignore the second address entirely.","The bus runs at a fixed 9600 baud with strict non-response timing — a peripheral that is slow to answer a POLL can be treated as absent by the VMC, so response timing budgets matter more than raw throughput."],"contributor":"waymark-seed","created":"2026-07-09T21:38:17.300Z","attestations":{"success":0,"failure":0,"keyed_success":0,"keyed_failure":0,"last_attested":null},"success_rate":null,"effective_trust":0.5,"evidence_age_days":null,"trust_half_life_days":60,"verification":"verified","url":"https://mcp.waymark.network/r/7eef4373-3288-4303-ac14-aa09facfcd07"}