Job Description
Role: Embedded C Developer – OpenSync/OpenWrt WiFi Router with Cellular Backup
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Location: Englewood, CO – Onsite
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Rate: $48/hr on W2 without benefits
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Fulltime/Contract role
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Job description:
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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 OpenWrt-based hardware running the OpenSync framework, with direct impact on millions of deployed customer premises equipment (CPE).
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Responsibilities
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• Design, develop, and debug embedded C software for Linux-based residential gateway platforms (ARM/MIPS SoC)
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• Develop and maintain OpenSync managers — event-driven daemons that interact with OVSDB for cloud-managed configuration and state reporting
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• Implement and optimize LTE/5G cellular failover and fallback logic including modem management, route arbitration, and WAN healthchecks
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• Develop LED state machine logic to provide accurate device status indication across complex multi-WAN scenarios
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• Interface with cellular modems via AT commands, QMI/MBIM, USB, and PCIe (MHI) protocols
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• Work with WiFi drivers (Qualcomm/Broadcom/Atheros) for 2.4GHz, 5GHz, and 6GHz radio configuration
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• Debug kernel-level issues including PCIe enumeration, USB device management, network driver crashes, and kernel panics
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• Implement and maintain secure communication channels using TLS with mutual authentication and tunneling protocols
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• Analyze and resolve field issues using device logs, crash dumps, and remote diagnostics
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• Develop init scripts, UCI configuration handlers, and persistent storage management for OpenWrt
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• Write unit tests and participate in code reviews via GitLab merge requests
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• Collaborate with hardware teams, QA, cloud platform engineers, and service provider partners
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Required Skills
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• 5+ years of embedded C development on Linux-based platforms
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• Strong proficiency in C programming — pointers, memory management, IPC, event-driven architectures
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• Experience with OpenWrt build system, package management, UCI configuration, and JFFS2/SquashFS overlay filesystems
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• Familiarity with OpenSync or similar cloud-managed CPE frameworks (OVSDB, protobuf, MQTT telemetry)
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• Experience with cellular modem integration — AT commands, QMI, network interface management (rmnet/wwan)
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• Strong understanding of Linux networking — routing tables, metrics, netfilter, bridge interfaces, IPv4 and IPv6 dual-stack, neighbor discovery, DHCPv4/DHCPv6, SLAAC, and prefix delegation
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• Understanding of TLS handshake with mutual authentication using X.509 certificates, certificate chain validation, and secure provisioning
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• Knowledge of security and tunneling protocols — GRE tunneling, IPsec, VPN overlays, and secure encapsulation for cloud-managed traffic
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• Experience with event loop frameworks (libev, libuv, or similar)
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• Proficiency with debugging tools — GDB, strace, tcpdump, kernel logs, serial console
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• Familiarity with Git, GitLab CI/CD, cross-compilation toolchains
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• Understanding of WiFi standards (802.11ax/be) and wireless driver configuration
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Preferred Skills
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• Experience with Qualcomm IPQ series SoCs (IPQ5018, IPQ9574) and NSS/PPE data path
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• Experience with Broadcom BCM series chipsets (BCM4908, BCM6750, BCM63178) and Memory Direct Engine (MDE) / hardware acceleration
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• Knowledge of Atheros/QCA/BCM wireless chipsets and CFG80211/mac80211 driver architecture
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• Knowledge of DOCSIS cable modem interaction and WAN interface management
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• Experience with PCIe and USB subsystems in embedded Linux (device enumeration, power management, error recovery)
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• Familiarity with eSIM/eUICC provisioning (LPA, GSMA SGP.22)
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• Experience with carrier aggregation, NR5G NSA/SA, and multi-band cellular configurations
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• Understanding of TR-069/TR-369 (USP) device management protocols
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• Basic understanding of TR-181 data model for CPE device management and service configuration
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• Experience with Kconfig-based build configuration
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• Knowledge of flash storage considerations — wear leveling, persistent partitions, factory reset flows
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• Familiarity with thermal management and power management (battery-powered CPE)
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Tools & Technologies
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• Languages: C, Shell scripting (sh/bash), Python (test automation)
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• OS/Platform: OpenWrt (Linux 5.x/6.x kernel), ARM Cortex-A53/A73
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• Frameworks: OpenSync, OVSDB, libev, protobuf-c, jansson (JSON)
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• Chipsets: Qualcomm IPQ, Broadcom BCM, Atheros/QCA
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• Networking: iproute2, iptables/nftables, ovsdb-server, hostapd/wpa_supplicant, GRE, IPsec
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• Security: OpenSSL/mbedTLS, X.509 certificates, mTLS, certificate management
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• Cellular: Qualcomm QCM/SDX modems, MHI, qcserial, AT+QENG/AT+COPS
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• Protocols: IPv4, IPv6, DHCPv4/v6, DNS, MQTT, GRE, TLS 1.2/1.3
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• Build: Make, Kconfig, OpenWrt feeds, cross-compilation (musl/glibc)
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• Debug: GDB, valgrind, serial console, logpull analysis
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• VCS/CI: Git, GitLab, merge request workflows
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Nice to Have
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• Experience working directly with ISP/MSO/OEM partners
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• Exposure to hardware bring-up and board support package (BSP) development
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• Experience with Agile/Scrum in a firmware development context
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• Familiarity with SCTE/DOCSIS standards
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• Understanding of TR-181 data model parameters for WAN management, WiFi configuration, and device monitoring
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• Experience with GRE tunnel implementation for backhaul traffic in managed WiFi deployments
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What You'll Work On
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• Cellular failover/fallback state machines with sub-second transition handling
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• LED indication logic for multi-WAN connectivity states
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• Modem health monitoring and subsystem restart/recovery
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• Internet reachability healthcheck frameworks
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• Cloud-managed device configuration and telemetry reporting via MQTT
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• Secure cloud connectivity using mTLS with X.509 certificate-based mutual authentication
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• GRE tunnel management for cloud-redirected traffic
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• Factory reset, firmware upgrade, and persistent storage management
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• IPv4/IPv6 dual-stack network configuration, routing, and failover across DOCSIS and LTE interfaces
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• WiFi radio configuration and performance optimization across Qualcomm / Broadcom platforms
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• Kernel crash analysis and driver-level bug resolution
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Top Skills:
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1. Embedded C Development on Linux/OpenWrt
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o C programming, Linux internals, debugging, IPC, event-driven design
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2. OpenSync/OpenWrt Platform Development
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o OpenSync Managers, OVSDB, UCI, MQTT, OpenWrt build system
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3. Linux Networking & LTE/5G Cellular Integration
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o Routing, IPv4/IPv6, failover, QMI/MBIM, modem management, GRE/IPsec
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Additional Details:
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Team size 8
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Direct report - None
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Key Deliverables :
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Responsibilities
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• Design, develop, and debug embedded C software for Linux-based residential gateway platforms (ARM/MIPS SoC)
\n
• Develop and maintain OpenSync managers — event-driven daemons that interact with OVSDB for cloud-managed configuration and state reporting
\n
• Implement and optimize LTE/5G cellular failover and fallback logic including modem management, route arbitration, and WAN healthchecks
\n
• Develop LED state machine logic to provide accurate device status indication across complex multi-WAN scenarios
\n
• Interface with cellular modems via AT commands, QMI/MBIM, USB, and PCIe (MHI) protocols
\n
• Work with WiFi drivers (Qualcomm/Broadcom/Atheros) for 2.4GHz, 5GHz, and 6GHz radio configuration
\n
• Debug kernel-level issues including PCIe enumeration, USB device management, network driver crashes, and kernel panics
\n
• Implement and maintain secure communication channels using TLS with mutual authentication and tunneling protocols
\n
• Analyze and resolve field issues using device logs, crash dumps, and remote diagnostics
\n
• Develop init scripts, UCI configuration handlers, and persistent storage management for OpenWrt
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• Write unit tests and participate in code reviews via GitLab merge requests
\n
• Collaborate with hardware teams, QA, cloud platform engineers, and service provider partners
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Unique selling points - Strong - Hands-on experience developing OpenSync-based OpenWrt gateway firmware with LTE/5G cellular failover, combining deep Embedded C expertise, Linux networking, and cloud-managed CPE platforms.
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