nRF5340 DK + MCP2515/TJA1050 module — can_start() always returns -EIO even in loop-back

Question

Draft — ready to post on Nordic DevZone / Zephyr mailing-list Title nRF5340 DK + MCP2515/TJA1050 module — can_start() always returns -EIO even in loop-back Hardware Item Details MCU board nRF5340 DK (core cpuapp ) CAN module “MCP2515 CAN-BUS Module” (blue/green PCB) with on-board TJA1050 transceiver SPI wiring SCK P0.04, MOSI P0.05, MISO P0.06, CS P1.09 INT P1.15 — declared GPIO_ACTIVE_LOW Supply VCC = 5 V, MCP2515 crystal 8 MHz (confirmed on OSC2 pin with scope) Software Zephyr 4.1 (commit 82b802f9ab4e) prj.conf CONFIG_GPIO =y CONFIG_PINCTRL =y CONFIG_SPI =y CONFIG_CAN =y CONFIG_CAN_MCP2515 =y CONFIG_LOG =y CONFIG_CAN_MCP2515_LOG_LEVEL_DBG =y CONFIG_PRINTK =y CONFIG_MAIN_STACK_SIZE =2048 Devicetree overlay (extract) & spi3 { status = "okay" ; pinctrl-0 = < & spi3_default >; pinctrl-1 = < & spi3_sleep >; pinctrl-names = "default" , "sleep" ; cs-gpios = < & gpio1 9 GPIO_ACTIVE_LOW >; mcp2515: can0 @ 0 { /* label: mcp2515 unit-addr: 0 */ compatible = "microchip,mcp2515" ; reg = < 0 >; spi-max-frequency = < 1000000 >; osc-freq = < 8000000 >; int-gpios = < & gpio1 15 GPIO_ACTIVE_LOW >; bus-speed = < 250000 >; status = "okay" ; label = "CAN_0" ; }; }; /* <-- et là aussi : }; */ /* On coupe les SPIM pour éviter l’avertissement pinctrl */ & spi0 { status = "disabled" ; }; & spi1 { status = "disabled" ; }; & spi2 { status = "disabled" ; }; & spi4 { status = "disabled" ; }; main.c: /* TX – src/main.c */ #include #include #include #include #include /* TX – test loop-back interne MCP2515 * Zephyr 4.1 – nRF5340 DK (core app) */ /* --------- LED alias --------- */ #define LED0_NODE DT_ALIAS (led0) static const struct gpio_dt_spec led = GPIO_DT_SPEC_GET ( LED0_NODE , gpios); /* --------- Contrôleur CAN --------- */ static const struct device * const can_dev = DEVICE_DT_GET ( DT_NODELABEL (mcp2515)); static const struct device * const spi3_dev = DEVICE_DT_GET ( DT_NODELABEL (spi3)); /* File de réception – 5 messages max, alignement 4 B */ K_MSGQ_DEFINE ( rx_msgq , sizeof ( struct can_frame ), 5 , 4 ); void main ( void ) { /* 1) Vérification des périphériques */ if ( ! device_is_ready ( led . port ) || ! device_is_ready ( can_dev ) || ! device_is_ready ( spi3_dev )) { printk ( "priphes pas pret " ); return ; } gpio_pin_configure_dt ( & led , GPIO_OUTPUT_INACTIVE ); /* ---------- test SPI brut -------------------------------------- */ uint8_t tx_buf [ 3 ] = { 0x03 , 0x0E , 0x00 }; /* READ + addr + dummy */ uint8_t rx_buf [ 3 ]; const struct spi_buf tx = { . buf = tx_buf , . len = 3 }; const struct spi_buf rx = { . buf = rx_buf , . len = 3 }; const struct spi_buf_set tx_set = { . buffers = & tx , . count = 1 }; const struct spi_buf_set rx_set = { . buffers = & rx , . count = 1 }; static const struct spi_cs_control spi3_cs = { . gpio = GPIO_DT_SPEC_GET ( DT_NODELABEL (spi3), cs_gpios), . delay = 0 }; static const struct spi_config spi_cfg = { . frequency = 1000000 , . operation = SPI_OP_MODE_MASTER | SPI_WORD_SET ( 8 ) | SPI_TRANSFER_MSB , . slave = 0 , . cs = spi3_cs , }; int spi_err = spi_transceive ( spi3_dev , & spi_cfg , & tx_set , & rx_set ); printk ( "SPI test -> %d , status byte = 0x %02X , CANSTAT = 0x %02X " , spi_err , rx_buf [ 1 ], rx_buf [ 2 ]); /* 2) Mode LOOPBACK **avant** can_start() */ can_set_mode ( can_dev , CAN_MODE_LOOPBACK ); int ret = can_start ( can_dev ); printk ( "can_start ret = %d " , ret ); if ( ret ) return ; /* 4) Filtre pour récupérer nos propres trames */ const struct can_filter filter = { . id = 0x123 , . mask = CAN_STD_ID_MASK , . flags = 0 /* trame standard */ }; can_add_rx_filter_msgq ( can_dev , & rx_msgq , & filter ); printk ( "== LOOPBACK actif – envoi toutes les 100 ms == " ); /* Trame à émettre (réutilisée à chaque tour) */ struct can_frame frame = { . id = 0x123 , . flags = 0 , /* standard */ . dlc = 2 , . data = { 0xAA , 0x55 }, }; /* 5) Boucle principale */ while ( 1 ) { /* Envoi non bloquant : retourne 0 ou -EAGAIN si buffers pleins */ int err = can_send ( can_dev , & frame , K_NO_WAIT , NULL , NULL ); printk ( "can_send -> %d " , err ); /* Lecture (non bloquante) de la trame renvoyée par loop-back */ struct can_frame rx ; if ( k_msgq_get ( & rx_msgq , & rx , K_MSEC ( 10 )) == 0 ) { printk ( "Reçue : %02X %02X " , rx . data [ 0 ], rx . data [ 1 ]); } gpio_pin_toggle_dt ( & led ); /* témoin visuel */ k_msleep ( 100 ); } } The application sets loop-back mode right after can_start() . What I see on the console *** Booting Zephyr OS build v4.1.0-4196-g82b802f9ab4e *** SPI test -> 0, CANSTAT = 0x00 can_start ret = -5 /* -EIO */ A manual spi_transceive() right before can_start() succeeds ( err = 0 ) but always reads 0x00 from CANSTAT. Therefore Zephyr’s driver ( can_mcp2515 ) aborts and returns -EIO. What I have already checked Power rails VCC on module = 5.08 V 3V3 regulator output = 3.30 V MCP2515 VDD (pin 3) = 5.08 V sheifl level between GPIO nrf5340 and MCP2515 Oscillator Stable 8 MHz square wave on MCP2515 OSC2 (pin 10) RESET̅ (pin 20) is high (≈ 5 V) CS toggles low during every SPI frame (scope) INT , stays high — I never see a low pulse osc-freq set to 8 MHz, re-built with --pristine Re-tested with a second brand-new module — same result. Question(s) Under Zephyr, does the MCP2515 driver rely on INT going low before it accepts that the device has reached “Configuration” mode? I never see INT toggle. Are there additional registers (CLKOUT, CNF1-3, …) that must be written manually when using an 8 MHz crystal? All examples I found assume 16 MHz. Any other reason why the driver would keep reading CANSTAT = 0×00 while the oscillator is running and RESET̅ is high? I’ve been stuck for several days — any hint or experience with 8 MHz MCP2515 modules on nRF5340 would be greatly appreciated!