topic Re: Freemaster over CAN based on s32k358 in FreeMASTER

Freemaster over CAN based on s32k358

BillWen — Wed, 28 Jan 2026 07:04:46 GMT

Hi :

Currently, we want to use freemaster over CAN bus so that I need to change setting from LPUART to CAN. I already check the related post by other author. The following is my setting in freemaster_cfg.h file for now.

// Select communication interface
//#define FMSTR_TRANSPORT FMSTR_SERIAL // Use serial transport layer
//#define FMSTR_SERIAL_DRV FMSTR_SERIAL_S32_LPUART/*FMSTR_SERIAL_S32K3XX_LPUART*/ // Use serial driver for UART

#define FMSTR_TRANSPORT FMSTR_CAN // Use serial transport layer
#define FMSTR_CAN_DRV FMSTR_CAN_S32_FLEXCAN // Use serial driver for CAN

/* Select RX and TX FlexCAN Message buffers */
#define FMSTR_FLEXCAN_TXMB 2
#define FMSTR_FLEXCAN_RXMB 0

in main.c
/* Initializes FreeMASTER */
//FMSTR_SerialSetBaseAddress((FMSTR_ADDR)IP_LPUART_1_BASE);
FMSTR_CanSetBaseAddress((FMSTR_ADDR)IP_CAN_0_BASE);
FMSTR_Init();

I have some question:

1. I already can send or receive can message by Can0, I want to send can message in other task and communicate freemaster by different can hardwareobject in the same time, is it possible?

2. I need define can hardware object for FMSTR_FLEXCAN_TXMB and FMSTR_FLEXCAN_RXMB?

3. Where should I add FMSTR_CanIsr function for interrupt?

4. Freemaster can detect my board when I use S32DS to debug in the beginning but can't detect board after a while, the following is my test result

Can you help me to check if I miss any setting in side my project? Really need help, thanks.

Thanks

BR, BillWen

Re: Freemaster over CAN based on s32k358

iulian_stan — Wed, 28 Jan 2026 14:23:31 GMT

Hi @BillWen,

1. Just to make sure I understood your intent correctly - you ask if the same CAN0 instance can be used by 2 different tasks: a) FreeMASTER and b) your own task.
So far we've been using a dedicated CAN instance for FreeMASTER exclusively, so I would need to check it. In theory it should be possible:

first you need to make sure that FreeMASTER and the other task use dedicated message buffers (can hardware objects)
considering that a single interrupt is raised for groups of 32 message buffers, the message buffers used by FreeMASTER and your task should be allocated in separate groups. Ex: 0,1 - FreeMASTER, 32,33 - your task.
Otherwise, you would need to implement a custom interrupt handler that would check which message buffer triggered the interrupt and based on this information invoke the corresponding routine.

2. No you don't need to define hardware objects for FreeMASTER explicitly. It will be done by FreeMASTER based on the configuration:

/** message buffers are defined in freemaster_cfg.h **/ #define FMSTR_FLEXCAN_TXMB 0 #define FMSTR_FLEXCAN_RXMB 1 /** message ids are defined in freemaster_can.h **/ #define FMSTR_CAN_CMDID 0x7AAU #define FMSTR_CAN_RESPID 0x7AAU

3. You can add interrupt configurations in Platform → Interrupt Controller

4. There may be multiple causes for this one:
a) in polling mode - there is big delay in between FMSTR_Poll calls
b) in interrupt mode - there are other interrupts that take priority other FreeMASTER
This is much dependent on the application that is running along side FreeMASTER. You would need to find a proper tradeoff based on your application.
I would start by temporarily disabling the custom logic or allocating a higher priority to FreeMASTER to confirm whether it is indeed the case.

Re: Freemaster over CAN based on s32k358

BillWen — Thu, 29 Jan 2026 01:14:24 GMT

Hi iulian_stan:

I use FlexCan_2 to implement, the following is my setting in freemaster_cfg.h file.

*The initial code inside main.c:

/* Initializes FreeMASTER */
//FMSTR_SerialSetBaseAddress((FMSTR_ADDR)IP_LPUART_1_BASE);
FMSTR_CanSetBaseAddress((FMSTR_ADDR)IP_CAN_2_BASE);
FMSTR_Init();

*The interrupt setting inside MCAL

I remove all canhardwareobject of flexcan2, only config cancotroller, and I didn't use flexcan2 in other task. But still can't connect freemaster. Do have any other idea?

Thanks

BR, BillWen

Re: Freemaster over CAN based on s32k358

iulian_stan — Thu, 29 Jan 2026 12:29:42 GMT

Hi @BillWen,

The first thing I noticed is that you configured FreeMASTER to use the first 2 message buffers (0,1) of CAN2, but interrupt handler is assigned to FlexCAN2_1_IRQn which corresponds to MB 32-63. Can you update it so FMSTR_CanIsr is executed.

Here are some more steps to troubleshoot FreeMASTER in case the above does not help:

1. Switch to polling mode and add enable debug TX

#define FMSTR_POLL_DRIVEN 1 #define FMSTR_DEBUG_TX 1

In this configuration FreeMASTER Driver will continuously send a test frame 0xA9U (+@W).
Note: you don't need to make any other changes to the interrupt.

2. Connect a logic analyzer and check if the test frame is actually sent.

These 2 steps will allow you to understand if the peripheral is properly configured.

If you can see the messages, you can disable the debug mode and try connecting to the board with FreeMASTER desktop tool. This will show if the polling mode works.
Note: make sure that Fmstr_Poll function is called continuously without big delays.

Next, after confirming that communication is functional you can switch back to interrupt mode. Eventually, start a debug session and set a break point in FMSTR_CanIsr to confirm that the interrupt is actually triggered.

Re: Freemaster over CAN based on s32k358

BillWen — Fri, 30 Jan 2026 05:37:43 GMT

Hi @iulian_stan :

For the setting about interrupt setting, I change it to FlexCAN2_0_IRQn but "FMSTR_CanIsr" didn't execute. Original it will run if I set FlexCAN2_1_IRQn. (I already remove any can hardwareobject for flexcan2, I only set can controller)

1. The following is the freemaster log if connect successful, but it seems still wrong.

I also can get 0x7aa can ID by PCAN-VIEW

So I think freemaster sent tx successfully but s32k358 didn't reply or something, do you have any idea?

Thanks
BR, BillWen

Re: Freemaster over CAN based on s32k358

BillWen — Fri, 30 Jan 2026 08:03:09 GMT

Hi @iulian_stan :
I think the problem is that I don't need to set Can_43_flexcan MCAL setting for the method you mentioned. I need to use driver layer flexcan_ip to implement?
Thanks
BR, BillWen

Re: Freemaster over CAN based on s32k358

iulian_stan — Fri, 30 Jan 2026 10:45:25 GMT

You are right about the interrupt - I missed that the first (_0_IRQn) is triggered by buss off state.

The communication log shows that the requests return timeout error (0x858E0003) even in the detection phase. After you stop connection and try to connect again, does this behavior repeats:
- a few successful requests followed by timeout
or you need to reset the board to be able to get any successful messages from the board ?

Re: Freemaster over CAN based on s32k358

iulian_stan — Fri, 30 Jan 2026 09:40:25 GMT

FreeMASTER functionality should not be affected by the layer on which the CAN peripheral is configured (MCAL or Drivers). Still, there may be extra configurations that are no displayed on the configuration screen that affect FreeMASTER Driver.
Ex: an older version of SDK was enabling CAN abort mechanism (CAN->MCR[AEN]). This was not handled by FreeMASTER and had be disabled manually.

What RTD version are you using ? I will try to check it on my side.

Re: Freemaster over CAN based on s32k358

BillWen — Mon, 02 Feb 2026 00:46:02 GMT

Hi @iulian_stan :
We use RTD3.0.0 version, but we won't update RTD to new version temporarily.
Due to our project, we need use MCAL (Flexcan_43 and canif), so I think I need create different can hardwareobject for different function. Use canif rx callback to execute freemaster interrupt I think, do you have any suggestion?

Thanks
BR, BillWen

Re: Freemaster over CAN based on s32k358

iulian_stan — Mon, 02 Feb 2026 18:41:51 GMT

Hi @BillWen,

I attached 2 example applications. They use RTD 3.0.0 and FreeMASTER 1.5.0 and contain minimal setup for FreeMASTER communication over CAN configured with S32 Configuration Tools (one using MCAL and another one - Drivers layer).

Hope it helps.

Re: Freemaster over CAN based on s32k358

BillWen — Tue, 03 Feb 2026 07:28:53 GMT

Hi @iulian_stan :

First of all, Thanks for your reply.

I change two setting of your flexcan example, and still can not work, can you help me check please?

1. I change flexcan from flexcan0 to flexcan2

2. I add standby pin for flexcan2 can transceiver

That's all, connect to flexcan2 and use any one freemaster project, load elf file which build from this example. Just can't connect.

I use RD-K358BMU this NXP board to test, if you have this board maybe you can try it, thanks again.

Thanks

BR, BillWen

Re: Freemaster over CAN based on s32k358

iulian_stan — Tue, 03 Feb 2026 16:04:45 GMT

Hi @BillWen,

I checked your application on my validation board and it worked as expected. RD-K358BMU may require some specific configurations. I will check it with that board and come back once I have any updates.

Re: Freemaster over CAN based on s32k358

iulian_stan — Tue, 03 Feb 2026 18:30:47 GMT

Update: I noticed that CAN2_RX and TCAN2_TX signals are routed to PTC16 and PTC17 respectively on RD-K358BMU

Your application configures TPC6 and PTC7. After updating PINS configuration I was able to connect FreeMASTER to the board

Re: Freemaster over CAN based on s32k358

BillWen — Wed, 04 Feb 2026 00:34:01 GMT

Hi @iulian_stan :

I already change pin to PTC16 & PTC17, still can't work. (Thanks for your noticed, due to our different project so that I change wrong pin)

Waiting for your good news, I have no idea for now, thanks again.

Thanks

BR, BillWen