ESP32 Forum

I'm working on a bare-metal code for the ESP32-H2, and I can't get an interrupt from a GPIO pin. If this is the wrong place to raise this, I'm sorry - where should I raise it?

Using the Technical Reference Manual Pre-release v0.4. (0.5 doesn't have any updates in sections 1, 6, 9)

Enabling the interrupt

Following TRM 1.6.3.2,

(0) Allocate a so-far-unused machine interrupt (1).

(1) Save the state of MIE and clear it.

(2) I'm going to use edge interrupts, so I set bit 1 in INTPRI_CORE0_CPU_INT_TYPE_REG. (By the way, doesn't this mean that all interrupts from GPIO have to have the same edge/level setting? and is edge/level here the same as edge/level for GPIO pins?)

(3) Set the priority in INTPRI_CORE0_CPU_INT_PRI_1_REG to 15.

(4) Set bit 1 of INTPRI_CORE0_CPU_INT_ENABLE_REG.

(4A) (not in TRM 1.6.3.2; in 9.5.3.1) Set the machine interrupt, 1, in INTMTX_CORE0_GPIO_INTR_MAP_REG.

(5) fence.

(6) Set the new machine interrupt bit (1) in the saved MIE, and restore it to MIE.

Configuring GPIO_3

(1) Configure GPIO_3 to function 1; set IO_MUX_GPIO3_MCU_SEL to 1. (This didn't seem to make any difference).

(2) Disable output by setting bit 3 in GPIO_ENABLE_W1TC_REG (is this right? using W1TS made no difference).

(3) Enable input by setting IO_MUX_GPIO3_FUN_IE to 1.

(4) Enable pull-up by setting IO_MUX_GPIO3_FUN_WPU to 1 and IO_MUX_GPIO3_FUN_WPD to 0.

(5) Set trigger type to any edge by setting GPIO_PIN3_INT_TYPE to 3.

(6) Enable interrupts by setting GPIO_PIN3_INT_ENA to 1 (ordinary interrupt).

Usage

Connecting GPIO_1 to ground doesn't generate an interrupt (but GPIO_IN_REG[3] goes to 0).

Hi,

I have forwarded your questions to our support team. I will get back to you once I receive a reply.

I believe there's a typo at the end with GPIO_1. Did you mean GPIO_3?

Also, could you possibly share your code? Could be something is wrong in your implementation.

Apologies for late reply: I was on leave.

You're quite right about my referencing GPIO_1 at the end; I meant GPIO_3.

I will point you to my code, but it's in Ada, so may not help much.

Setting up interrupts: https://github.com/simonjwright/FreeRTO ... iemiha.adb (note, at line 154 I've only dealt with GPIO, will address the others after I've got this one working).

Setting up GPIO & enabling interrupt: https://github.com/simonjwright/esp32h2 ... l-gpio.adb

In TRM 1.6.3.2(1), it says "save the state of MIE and clear MIE to 0". I had assumed that it meant the MIE CSR, but maybe it meant the MIE bit in MSTATUS?

I’ve tried this, but it made no difference.

I did notice that when I began the procedure, MSTATUS had both MIE and MPIE set, which is I think contrary to TRM 1.6.2.
It says

Upon execution of MRET/URET instruction, the CPU [...] copies the state of MPIE/UPIE back into MIE/UIE, and subsequently clears MPIE/UPIE. This means that if previously MPIE/UPIE was set, then, after MRET/URET, MIE/UIE will be set, thereby enabling interrupts globally.

. On the other hand, the only interrupt enabled was the timer (7), and it probably hadn’t run yet.

Hi,

Please consider if the GPIO interrupt source has been successfully assigned to the CPU interrupt. Try the debugging method:

• Read GPIO_STATUS_REG (0×0044) to check if GPIO interrupt is generated.

• Set INTMTX_CORE0_CPU_INTR_FROM_CPU_0_MAP_REG (0×001C) to 1, then set INTPRI_CPU_INTR_FROM_CPU_0_REG (0×0090) to 1, to check if CPU interrupt configuration is correct. You can also try another CPU interrupt number.

Let me know if it helps. Thanks.

Many apologies for my delay in replying.

Read GPIO_STATUS_REG (0×0044) to check if GPIO interrupt is generated.

I tried this, it had bit 22 set as expected.

Set INTMTX_CORE0_CPU_INTR_FROM_CPU_0_MAP_REG (0×001C) to 1, then set INTPRI_CPU_INTR_FROM_CPU_0_REG (0×0090) to 1, to check if CPU interrupt configuration is correct. You can also try another CPU interrupt number.

This didn't seem to make any difference, though I may have misunderstood your suggestion.

Anyway! I can now report that, without my being quite sure about what change had the effect, I'm now getting interrupts! Next step, to clear them.

Thanks for your assistance.

Hi,

Thanks for the update!