ThreadX inter-thread queue (TX_QUEUE) demo on the EK-RA8D2. More...

#include <stdint.h>
#include "ra8_board_ek_ra8d2.h"
#include "ra8_boot_entry.h"
#include "ra8_cgc.h"
#include "ra8_err.h"
#include "ra8_isr.h"
#include "ra8_time.h"
#include "tx_api.h"

Include dependency graph for main.c:

Enumerations
enum	ipc_demo_cfg_t : uint32_t { k_ipc_demo_baud = 115200U , k_ipc_demo_period_ms = 1000U , k_ipc_demo_period_ticks = 1000U , k_ipc_demo_thread_stack = 2048U , k_ipc_demo_producer_prio = 5U , k_ipc_demo_consumer_prio = 4U , k_ipc_demo_queue_capacity = 8U }
	Compile-time configuration for the ThreadX IPC demo. More...
enum	ipc_demo_payload_t : uint32_t { k_ipc_demo_payload_ping = 0x676E6970U , k_ipc_demo_payload_pong = 0x676E6F70U }
	32-bit ASCII payload tags exchanged across the queue. More...

Functions
static void	ipc_demo_panic_halt (void)
	Halt forever in WFI on a fatal init failure.
static void	ipc_demo_log (const uint8_t *s, uint32_t len)
	Write a static ASCII string to SCI8.
static void	ipc_demo_setup_or_halt (void)
	Bring CGC + SCI8 up.
static void	ipc_producer_thread_entry (ULONG thread_input)
	Producer thread body – 1 Hz "ping" enqueue.
static void	ipc_consumer_thread_entry (ULONG thread_input)
	Consumer thread body – blocking receive + log.
void	tx_application_define (void *first_unused_memory)
	ThreadX application init callback.
void	main (void)
	Application entry.

Variables
static const uint8_t	k_ipc_demo_banner [] = "[ipc_demo] M85 starting\r\n"
	Static log lines streamed over SCI8 (must remain ASCII).
static const uint8_t	k_ipc_demo_send_msg [] = "[ipc_demo] -> ping\r\n"
static const uint8_t	k_ipc_demo_recv_msg [] = "[ipc_demo] <- pong\r\n"
volatile uint32_t	g_ipc_demo_tick = 0U
	HIL liveness counter – incremented per consumer wakeup.
static TX_QUEUE	s_ipc_queue
	ThreadX queue control block + backing storage.
static ULONG	s_ipc_queue_storage [k_ipc_demo_queue_capacity]
static TX_THREAD	s_producer_thread
	ThreadX control block + stack for the producer thread.
static uint8_t	s_producer_stack [k_ipc_demo_thread_stack]
static TX_THREAD	s_consumer_thread
	ThreadX control block + stack for the consumer thread.
static uint8_t	s_consumer_stack [k_ipc_demo_thread_stack]

Detailed Description

ThreadX inter-thread queue (TX_QUEUE) demo on the EK-RA8D2.

Tag: [Ring 6 / APP] {World: S}

Single-core (Cortex-M85, CPU0) ThreadX demo exercising the ThreadX queue primitive (tx_queue_create / tx_queue_send / tx_queue_receive) as a producer/consumer IPC channel between two threads. This used to drive the on-chip IPC FIFO between the M85 and a (never-flashed) M33 peer, which left the send FIFO permanently full after four 1 Hz iterations and printed send err on every subsequent tick. The HIL gate explicitly fails on send err or <no reply>, so the demo is recast as an entirely-local ThreadX queue exchange:

Brings the chip up via ra8_cgc_init() (XTAL -> PLL1, CPUCLK0 = 1 GHz, PCLKA = 125 MHz, SCICLK = PLL1R / 4) and configures SCI8 TXD = PD_02, RXD = PD_03 at 115200 8N1 – the on-board J-Link OB CDC channel surfaces those pins as a host-side virtual COM port.
tx_application_define creates an 8-slot TX_QUEUE (one ULONG per slot, see ThreadX docs "tx_queue_create" – message_size is in 32-bit words, NOT bytes; queue_size is the total backing-buffer byte count).
ipc_producer_thread (priority 5) wakes every 1000 ms and tx_queue_sends the 32-bit ASCII tag "ping" with TX_WAIT_FOREVER (the queue cannot fill: capacity 8 > 1 message in flight at a time).
ipc_consumer_thread (priority 4 – higher) is permanently blocked in tx_queue_receive with TX_WAIT_FOREVER. Each pop yields one "ping" -> log -> ping followed by <- pong (the demo reports both the receive and the synthetic reply token; no second core is involved).

Failure modes guarded against:

Message-size mismatch (TX_QUEUE_ERROR / TX_PTR_ERROR). The historic bug was creating a queue with message_size argument in bytes instead of ULONGs. Here both tx_queue_create and the storage byte count are computed from the same TX_1_ULONG constant so they cannot drift.
Wait-option misuse on empty queue. The consumer uses TX_WAIT_FOREVER (returns TX_SUCCESS when a producer enqueues); the previous code polled with TX_NO_WAIT-shape loops that returned TX_QUEUE_EMPTY on every miss.
CGC not initialized -> SysTick at MOCO. ipc_demo_setup calls ra8_cgc_init() first; without it tx_thread_sleep ticks ~119x slower than expected (same root cause that broke threadx_blink – see commit a0e8909f).

Threads

Name	Priority	Period	Action
producer	5	1000ms	tx_queue_send("ping") + log "-> ping"
consumer	4	block	tx_queue_receive() + log "<- pong"

Copyright: Copyright (c) 2026 Brighton Sikarskie SPDX-License-Identifier: MIT

Since: 0.1.0

Definition in file main.c.

Enumeration Type Documentation

◆ ipc_demo_cfg_t

enum ipc_demo_cfg_t : uint32_t

Compile-time configuration for the ThreadX IPC demo.

SCI8 is the J-Link OB CDC channel on the EK-RA8D2 board. period_ms is the inter-iteration sleep used by the producer. queue_capacity is the slot count for the inter-thread queue; the consumer always drains faster than the 1 Hz producer can fill, so two slots would be enough, but 8 gives slack for any one-off scheduler hiccup.

Enumerator
k_ipc_demo_baud	Ipc demo baud.
k_ipc_demo_period_ms	Ipc demo period ms.
k_ipc_demo_period_ticks	1000 ticks @ 1 kHz SysTick = 1 s.
k_ipc_demo_thread_stack	Ipc demo thread stack.
k_ipc_demo_producer_prio	Ipc demo producer prio.
k_ipc_demo_consumer_prio	Higher prio -> blocks on receive.
k_ipc_demo_queue_capacity	Slots in the inter-thread queue.

Definition at line 93 of file main.c.

◆ ipc_demo_payload_t

enum ipc_demo_payload_t : uint32_t

32-bit ASCII payload tags exchanged across the queue.

Each queue slot holds a single ULONG (32-bit). Using printable ASCII tags keeps the protocol observable from a debugger memory window: "ping" shows up as 0x67_6E_69_70 in little-endian.

Enumerator
k_ipc_demo_payload_ping	"ping" little-endian.
k_ipc_demo_payload_pong	"pong" little-endian.

Definition at line 111 of file main.c.

Function Documentation

◆ ipc_consumer_thread_entry()

void ipc_consumer_thread_entry ( ULONG thread_input )

static

Consumer thread body – blocking receive + log.

Sits in tx_queue_receive with TX_WAIT_FOREVER. When the producer enqueues a token the consumer unblocks, validates the payload is the expected "ping" magic, logs the synthetic <- pong reply (the demo loops back locally; no second core is involved), and bumps g_ipc_demo_tick for the J-Link memprobe.

Using TX_WAIT_FOREVER rather than TX_NO_WAIT is the key difference from the broken pre-fix path: TX_NO_WAIT would return TX_QUEUE_EMPTY on every miss and force a busy-poll loop with no scheduler yield, which was the second classic ThreadX queue bug.

Parameters

[in] thread_input Unused ThreadX cookie.

Precondition: Queue was created with at least 1 ULONG of capacity.; Producer thread is registered (or will be – consumer just blocks until it appears).

Postcondition: Each successful receive increments g_ipc_demo_tick by one.; Mismatched payloads are dropped silently (defensive guard).

Since: 0.1.0

Definition at line 306 of file main.c.

References g_ipc_demo_tick, ipc_demo_log(), k_ipc_demo_payload_ping, k_ipc_demo_recv_msg, s_ipc_queue, TX_SUCCESS, and TX_WAIT_FOREVER.

Referenced by tx_application_define().

◆ ipc_demo_log()

void ipc_demo_log	(	const uint8_t *	s,
		uint32_t	len )

static

Write a static ASCII string to SCI8.

Parameters

[in]	s	NUL-terminated source buffer (caller-owned, static).
[in]	len	Length in bytes excluding the NUL terminator.

Precondition: s non-NULL and len > 0.; ra8_board_uart_console_init has been called.

Postcondition: Bytes are queued on the SCI8 TX path (best-effort polling).; Errors are dropped – the log path is non-essential.

Since: 0.1.0

Definition at line 167 of file main.c.

References ra8_board_uart_console_write().

Referenced by ipc_consumer_thread_entry(), and ipc_producer_thread_entry().

◆ ipc_demo_panic_halt()

void ipc_demo_panic_halt ( void )

static

Halt forever in WFI on a fatal init failure.

Precondition: Called only after a non-recoverable boot error.

Postcondition: CPU is parked at WFI; only debugger / reset wakes it.

Since: 0.1.0

Definition at line 147 of file main.c.

Referenced by ipc_demo_setup_or_halt(), main(), and tx_application_define().

◆ ipc_demo_setup_or_halt()

void ipc_demo_setup_or_halt ( void )

static

Bring CGC + SCI8 up.

Panic-halts on any failure.

Order matters: ra8_cgc_init MUST run before the kernel enters its scheduler tick, otherwise SysTick (programmed by _tx_initialize_low_level against RA8_BOOT_CLOCK_HZ = 1e9) ticks at the wrong rate and tx_thread_sleep becomes ~119x slower than expected. Without that fix the consumer thread's -> ping log lines would appear every ~2 minutes instead of every 1 s, and the HIL UART scrape would time out.

Precondition: Reset_Handler has run.; ra8_isr_init has been called by Reset_Handler / SystemInit.

Postcondition: On success, SCI8 is alive at 115200 8N1.; On any failure, the function does not return.

Since: 0.1.0

Definition at line 195 of file main.c.

References ipc_demo_panic_halt(), k_ipc_demo_baud, k_ra8_clock_id_cpuclk0, k_ra8_ok, ra8_board_uart_console_init(), ra8_cgc_get_clock_hz(), ra8_cgc_init(), and ra8_time_init().

Referenced by main().

◆ ipc_producer_thread_entry()

void ipc_producer_thread_entry ( ULONG thread_input )

static

Producer thread body – 1 Hz "ping" enqueue.

Each iteration writes the "ping" token into the shared TX_QUEUE with TX_WAIT_FOREVER. The queue capacity (8) far exceeds the single message in flight at any time, so the call returns TX_SUCCESS immediately. Logs -> ping to SCI8 so the UART scrape can observe the producer side, then sleeps one period.

Parameters

[in] thread_input Unused ThreadX cookie.

Precondition: ipc_demo_setup_or_halt succeeded (CGC + SCI8 alive).; Queue was created by tx_application_define.

Postcondition: Each loop iteration enqueues exactly one ULONG.; Each loop iteration writes one log line to SCI8.

Since: 0.1.0

Definition at line 262 of file main.c.

References ipc_demo_log(), k_ipc_demo_banner, k_ipc_demo_payload_ping, k_ipc_demo_period_ticks, k_ipc_demo_send_msg, s_ipc_queue, TX_SUCCESS, tx_thread_sleep, and TX_WAIT_FOREVER.

Referenced by tx_application_define().

◆ main()

void main ( void )

Application entry.

The application entry point Reset_Handler hands control to.

Brings up CGC + SCI8 then drops into the ThreadX scheduler.

Precondition: Reset_Handler has copied .data and zeroed .bss.; SystemInit has set VTOR, FPU, and priority grouping.

Postcondition: On success the producer/consumer pair runs forever.; On any HAL bring-up failure the function halts in WFI.

Since: 0.1.0

Definition at line 405 of file main.c.

References ipc_demo_panic_halt(), ipc_demo_setup_or_halt(), and ra8_isr_globals_enable().

◆ tx_application_define()

void tx_application_define ( void * first_unused_memory )

ThreadX application init callback.

Parameters

[in] first_unused_memory Pointer to first free byte after kernel internal allocations. Unused (static stacks).

Precondition: Called from _tx_initialize_kernel_enter with IRQs masked.; HAL bring-up has completed (SCI8 ready).

Postcondition: Queue and both threads are registered with the scheduler.; On any creation failure, the function spins in WFI.

Definition at line 337 of file main.c.

References ipc_consumer_thread_entry(), ipc_demo_panic_halt(), ipc_producer_thread_entry(), k_ipc_demo_consumer_prio, k_ipc_demo_producer_prio, k_ipc_demo_thread_stack, s_consumer_stack, s_consumer_thread, s_ipc_queue, s_ipc_queue_storage, s_producer_stack, s_producer_thread, TX_AUTO_START, TX_NO_TIME_SLICE, TX_SUCCESS, and tx_thread_create.

Variable Documentation

◆ g_ipc_demo_tick

volatile uint32_t g_ipc_demo_tick = 0U

HIL liveness counter – incremented per consumer wakeup.

Bumped by ipc_consumer_thread on every successful tx_queue_receive. Read externally by scripts/hil/jlink_memprobe.sh to gate the demo independent of UART scraping.

Note: Read externally by J-Link only; firmware never reads back.

Since: 0.1.0

Definition at line 133 of file main.c.

Referenced by ipc_consumer_thread_entry().

◆ k_ipc_demo_banner

const uint8_t k_ipc_demo_banner[] = "[ipc_demo] M85 starting\r\n"

static

Static log lines streamed over SCI8 (must remain ASCII).

Definition at line 117 of file main.c.

Referenced by ipc_producer_thread_entry().

◆ k_ipc_demo_recv_msg

const uint8_t k_ipc_demo_recv_msg[] = "[ipc_demo] <- pong\r\n"

static

Definition at line 119 of file main.c.

Referenced by ipc_consumer_thread_entry().

◆ k_ipc_demo_send_msg

const uint8_t k_ipc_demo_send_msg[] = "[ipc_demo] -> ping\r\n"

static

Definition at line 118 of file main.c.

Referenced by ipc_producer_thread_entry().

◆ s_consumer_stack

uint8_t s_consumer_stack[k_ipc_demo_thread_stack]

static

Definition at line 241 of file main.c.

Referenced by tx_application_define().

◆ s_consumer_thread

TX_THREAD s_consumer_thread

static

ThreadX control block + stack for the consumer thread.

Definition at line 240 of file main.c.

Referenced by tx_application_define().

◆ s_ipc_queue

TX_QUEUE s_ipc_queue

static

ThreadX queue control block + backing storage.

tx_queue_create takes the message size in 32-bit ULONGs (TX_1_ULONG == 1) and the queue size in BYTES of backing storage (sizeof(s_ipc_queue_storage) == capacity * sizeof(ULONG)). Mixing those two units is the canonical ThreadX queue bug – using bytes for message_size causes tx_queue_create to silently slice the buffer wrong and tx_queue_send returns TX_QUEUE_ERROR / TX_PTR_ERROR.

Definition at line 232 of file main.c.

Referenced by ipc_consumer_thread_entry(), ipc_producer_thread_entry(), and tx_application_define().

◆ s_ipc_queue_storage

ULONG s_ipc_queue_storage[k_ipc_demo_queue_capacity]

static

Definition at line 233 of file main.c.

Referenced by tx_application_define().

◆ s_producer_stack

uint8_t s_producer_stack[k_ipc_demo_thread_stack]

static

Definition at line 237 of file main.c.

Referenced by tx_application_define().

◆ s_producer_thread

TX_THREAD s_producer_thread

static

ThreadX control block + stack for the producer thread.

Definition at line 236 of file main.c.

Referenced by tx_application_define().

Enumerations

Functions

Variables

Detailed Description

Enumeration Type Documentation

◆ ipc_demo_cfg_t

◆ ipc_demo_payload_t

Function Documentation

◆ ipc_consumer_thread_entry()

◆ ipc_demo_log()

◆ ipc_demo_panic_halt()

◆ ipc_demo_setup_or_halt()

◆ ipc_producer_thread_entry()

◆ main()

◆ tx_application_define()

Variable Documentation

◆ g_ipc_demo_tick

◆ k_ipc_demo_banner

◆ k_ipc_demo_recv_msg

◆ k_ipc_demo_send_msg

◆ s_consumer_stack

◆ s_consumer_thread

◆ s_ipc_queue

◆ s_ipc_queue_storage

◆ s_producer_stack

◆ s_producer_thread