Embedded C Developer

Embedded C Developer – Open Sync/Open Wrt WiFi Router with Cellular Backup

Location:

Onsite. Englewood, CO

JD:

We're looking for an Embedded C Developer to work on next-generation residential gateway platforms that combine DOCSIS/fiber WAN connectivity with LTE/5G cellular backup. You'll be developing and maintaining firmware on Open Wrt-based hardware running the Open Sync framework, with direct impact on millions of deployed customer premises equipment (CPE).

• Design, develop, and debug embedded C software for Linux-based residential gateway platforms (ARM/MIPS SoC)
• Develop and maintain Open Sync managers — event-driven daemons that interact with OVSDB for cloud-managed configuration and state reporting
• Implement and optimize LTE/5G cellular failover and fallback logic including modem management, route arbitration, and WAN health checks
• Develop LED state machine logic to provide accurate device status indication across complex multi-WAN scenarios
• Interface with cellular modems via AT commands, QMI/MBIM, USB, and PCIe (MHI) protocols
• Work with WiFi drivers (Qualcomm/Broadcom/Atheros) for 2.4GHz, 5GHz, and 6GHz radio configuration
• Debug kernel-level issues including PCIe enumeration, USB device management, network driver crashes, and kernel panics
• Implement and maintain secure communication channels using TLS with mutual authentication and tunneling protocols
• Analyze and resolve field issues using device logs, crash dumps, and remote diagnostics
• Develop init scripts, UCI configuration handlers, and persistent storage management for Open Wrt
• Write unit tests and participate in code reviews via Git Lab merge requests
• Collaborate with hardware teams, QA, cloud platform engineers, and service provider partners

• 5+ years of embedded C development on Linux-based platforms
• Strong proficiency in C programming — pointers, memory management, IPC, event-driven architectures
• Experience with Open Wrt build system, package management, UCI configuration, and JFFS2/SquashFS overlay file systems
• Familiarity with Open Sync or similar cloud-managed CPE frameworks (OVSDB, protobuf, MQTT telemetry)
• Experience with cellular modem integration — AT commands, QMI, network interface management (rmnet/wwan)
• Strong understanding of Linux networking — routing tables, metrics, netfilter, bridge interfaces, IPv4 and IPv6 dual-stack, neighbor discovery, DHCPv4/DHCPv6, SLAAC, and prefix delegation
• Understanding of TLS handshake with mutual authentication using X.509 certificates, certificate chain validation, and secure provisioning
• Knowledge of security and tunneling protocols — GRE tunneling, IPsec, VPN overlays, and secure encapsulation for cloud-managed traffic
• Experience with event loop frameworks (libev, libuv, or similar)
• Proficiency with debugging tools — GDB, strace, tcpdump, kernel logs, serial console
• Familiarity with Git, Git Lab CI/CD, cross-compilation tool chains
• Understanding of WiFi standards (802.11ax/be) and wireless driver configuration

• Experience with Qualcomm IPQ series SoCs (IPQ
  5018, IPQ
  9574) and NSS/PPE data path
• Experience with Broadcom BCM series chipsets (BCM
  4908, BCM
  6750, BCM
  63178) and Memory Direct Engine (MDE) / hardware acceleration
• Knowledge of Atheros/QCA/BCM wireless chipsets and CFG
  80211/mac
  80211 driver architecture
• Knowledge of DOCSIS cable modem interaction and WAN interface management
• Experience with PCIe and USB subsystems in embedded Linux (device enumeration, power management, error recovery)
• Familiarity with eSIM/eUICC provisioning (LPA, GSMA SGP.
  22)
• Experience with carrier aggregation, NR5G NSA/SA, and multi-band cellular configurations
• Understanding of TR-069/TR-369 (USP) device management protocols
• Basic understanding of TR-181 data model for CPE device management and service configuration
• Experience with Kconfig-based build configuration
• Knowledge of flash storage considerations — wear leveling, persistent partitions, factory reset flows
• Familiarity with thermal management and power management (battery-powered CPE)

• Networking: iproute2, iptables/nftables, ovsdb-server, hostapd/, GRE, IPsec
• Build:
  Make, Kconfig, Open Wrt feeds, cross-compilation…