// FreeRTOS · ISO 14229 UDS
A complete, YAML-configured UDS stack that generates production C source for FreeRTOS. Same codegen engine as the Zephyr variant — switch platforms by changing one config flag. Covers all 19 UDS services, CAN ISO-TP and DoIP transports, and ASIL-B safety wrappers. GPL v2 runtime is free on GitHub.
// FreeRTOS integration
FreeRTOS is the opposite problem to Zephyr. There is no devicetree and no CAN driver model, so nothing binds the stack to your controller for you — you own the driver, and the diagnostics stack has to meet you at a seam narrow enough to be worth owning.
EDS makes that seam two functions. You give it a send function, and you push received frames in from your own ISR or task:
/* you provide this */
void freertos_can_init(eds_can_send_fn_t can_send);
/* you call this from your CAN RX path */
void freertos_can_input(const eds_can_frame_t *frame);Everything above that seam — ISO-TP reassembly, session and security state, DID dispatch, NRC generation — is the same generated code a Zephyr build gets, from the same diagnostics_config.yaml. The contrast is worth stating plainly: on Zephyr you hand EDS a const struct device * and the RTOS supplies the driver; on FreeRTOS you supply it.
diagnostics_config.yaml (same for both RTOS targets)
ecu:
name: Sensor_MCU
platform: freertos # or: zephyr
addressing:
can_id_request: 0x640
can_id_response: 0x641
sessions:
- default
- extended
services:
- id: 0x22 # ReadDataByIdentifier
- id: 0x2E # WriteDataByIdentifier
- id: 0x27 # SecurityAccess
- id: 0x19 # ReadDTCInformation
- id: 0x14 # ClearDiagnosticInformation
- id: 0x3E # TesterPresent
dids:
- id: 0xF190
name: VIN
length: 17
read_sessions: [default, extended]
- id: 0xD001
name: Temperature_Raw
length: 4
read_sessions: [default, extended]Generated FreeRTOS output
python3 tools/codegen.py \
--config diagnostics_config.yaml \
--platform freertos \
--out build/ \
--safety-wrappers \
--asil-level B
build/
uds_server.c/.h # UDS dispatcher + FreeRTOS task
uds_dids.c/.h # DID handlers (no RTOS API)
uds_dtcs.c/.h # DTC storage (flash-backed)
uds_sessions.c/.h # session state machine
uds_security.c/.h # AES-128-CMAC SecurityAccess
uds_safety.c/.h # ASIL-B 5-step validation chain
uds_platform_freertos.c # FreeRTOS task + queue glue
test_uds.py # pytest suiteFreeRTOS task init
/* In your application startup */
#include "uds_server.h"
/* EDS creates its own task internally */
eds_init(&eds_config);
/* CAN receive hook — call from your ISR or CAN task */
void can_rx_callback(uint8_t *frame, size_t len) {
eds_isotp_rx(frame, len);
}The FreeRTOS platform layer maps EDS threading primitives to FreeRTOS equivalents. No global state. No polling loop. A single UDS task owns the ISO-TP reassembly buffer and calls into the generated handlers.
xTaskCreate with configurable stack size and priorityxQueueReceive from CAN RX, internal reassembly FSMxTimerCreate// example ECUs
The Developer and Professional tiers include specialist examples. Three ship specifically for FreeRTOS targets.
sensor_freertos example layout
examples/sensor_freertos/
diagnostics_config.yaml # ECU description
src/
main.c # FreeRTOS init + eds_init()
can_driver.c # board-specific CAN RX/TX
flash_backend.c # NVM adapter for DTC storage
build/
uds_server.c/.h # generated — do not edit
uds_dids.c/.h
uds_dtcs.c/.h
uds_safety.c/.h
uds_platform_freertos.c// pricing
The GPL v2 runtime is always free on GitHub. Developer adds the code generator, test generation, ARXML import and the AI CLI; Professional adds the ASIL-B safety artifacts and the harness. Annual licence, offline after activation.