Add busio support for ADI MAX32xxx port #10413

Brandon-Hurst · 2025-06-10T18:01:18Z

Add BUSIO Support for supported MAX32xxx devices. Not all capable MAX32 devices are supported yet; more support for MAX32650/MAX32666/MAX78002 boards may be added in a future PR. This module was tested on a MAX32690 board, the AD-APARD32690-SL. I used a ADT7140 I2C and MAX31723 SPI temperature sensor, and also tested the UART via the debug port serial connection.

BUSIO support added for MAX32 devices
Peripherals enumerated in peripherals/max32690 for MAX32690 MCU, including helper functions for mapping a set of pins to the associated on-chip peripheral
common-hal/busio contains the implementation of the BUSIO port functions

MAX31723 (SPI):

ADT7420 (I2C):

A simple echo test was done with UART as well with no issues:

from board import *
from busio import UART
 
# init uart with timeout of 10 seconds
uart = UART(P2_12, P2_11, baudrate=115200, timeout = 10.0)
 
# Write 'hello' to another serial port
uart.write('hello\n')
 
# Read 5 characters
uart.read(5)
 
# Read until newline
uart.readline()

- Enabled BUSIO in mpconfigport.mk - Stubs added for busio.I2C & busio.SPI - Implemented busio.UART to basic working functionality - Added MCU-specific UART data in peripherals/<mcu>/max32_uart.c & max32_uart.h - Still have a couple issues where UART generates garbage characters or does not respond to timeouts / generate asynchronous IRQs

- Add debug-dap.sh to spawn OpenOCD process & gdb-multiarch process for debugging. Requires MaximSDK install & path settings inside this script. Also depends on gdb-multiarch and connected CMSIS-DAP probe over USB. - debug-dap.gdb simply holds the gdb commands for this script + small style fix on common-hal/microcontroller/Pin.c

- Graceful recovery from timeouts added - Remaining issue still exists where a timeout occurs after a while

- No ISR for UART writes, but uses timeouts - Reads use ISRs, but also incorporate timeouts

- Formatting & codespell fixes from pre-commit

- Call NVIC_SetRAM in supervisor/port.c to move NVIC table to RAM, enabling ISR RAM remapping. - Rename UART ISR to be generic for any UART IRQn. - Remove background led writes from background.c.

- Data structure and constructor for I2C (tested) - Lock and probing functions complete and tested TODO: Implement I2C Write, Read, Wr/Rd Signed-off-by: Brandon-Hurst <[email protected]>

Currently coupled a bit to APARD32690-SL board. Will refactor after testing BUSIO.SPI Signed-off-by: Brandon-Hurst <[email protected]>

TODO: - Figure out assigning CS Pins for SPI - Test & Debug SPI / I2C Signed-off-by: Brandon-Hurst <[email protected]>

Signed-off-by: Brandon-Hurst <[email protected]>

…ipherals. Signed-off-by: Brandon-Hurst <[email protected]>

Also reformatted pinmaps for SPI/I2C/UART on MAX32690 Signed-off-by: Brandon Hurst <[email protected]>

- Fixed errors with peripheral bus hardware descriptions in MAX32690 "peripherals/" - Resolved all FIXME comments - Removed unused ringbuf API from common-hal/busio/UART.c Signed-off-by: Brandon Hurst <[email protected]>

Signed-off-by: Brandon Hurst <[email protected]>

- Add correct ringbuffer handling code to ports/analog/common-hal/UART.c Signed-off-by: Brandon Hurst <[email protected]>

Signed-off-by: Brandon Hurst <[email protected]>

- Used direct hardware values to rely on common HW implementation - Accounted for TX Lockout conditions in Transmit FIFO causing errors Signed-off-by: Brandon Hurst <[email protected]>

Signed-off-by: Brandon Hurst <[email protected]>

- Probe function caused infinite loops / unreliable ACK values - Replaced with probe-function with low-level routines Signed-off-by: Brandon Hurst <[email protected]>

Signed-off-by: Brandon Hurst <[email protected]>

dhalbert

Thanks for continuing to flesh this out. The changes here are stylistic, to match how we do error messages, etc. elsewhere.

dhalbert · 2025-06-12T17:27:08Z

ports/analog/common-hal/busio/I2C.c

+    if ((scl != NULL) && (sda != NULL)) {
+        MXC_GPIO_Config(&i2c_maps[self->i2c_id]);
+        err = MXC_I2C_Init(self->i2c_regs, 1, 0x00);
+        if (err) {
+            mp_raise_RuntimeError_varg(MP_ERROR_TEXT("Failed to init I2C. ERR: %d\n"), err);
+        }
+        err = MXC_I2C_SetFrequency(self->i2c_regs, frequency);
+        if (err < 0) {
+            mp_raise_RuntimeError_varg(MP_ERROR_TEXT("Failed to set I2C frequency. ERR: %d\n"), err);
+        }
+    } else if (scl != NULL) {
+        mp_raise_NotImplementedError(MP_ERROR_TEXT("I2C needs SDA & SCL"));
+    } else if (sda != NULL) {
+        mp_raise_NotImplementedError(MP_ERROR_TEXT("I2C needs SDA & SCL"));
+    } else {
+        // Should not get here, as shared-bindings API should not call this way
+    }


The validate_obj_is_free_pin() calls in shared-bindings/busio/I2C.c will ensure that scl and sda are both pins and cannot be null, so you can remove this validation.

dhalbert · 2025-06-12T17:29:36Z

ports/analog/common-hal/busio/I2C.c

+    if (((timeout < 0.0) || (timeout > 100.0))) {
+        self->timeout = 1.0;
+    } else {
+        self->timeout = timeout;
+    }


The timeout that is passed in is a uint32_t, so don't compare against floats. Also self->timeout is a uint32_t, so there shouldn't be any floats here at all.

dhalbert · 2025-06-12T17:35:41Z

ports/analog/common-hal/busio/I2C.c

+    };
+    ret = MXC_I2C_MasterTransaction(&rd_req);
+    if (ret) {
+        mp_raise_RuntimeError(MP_ERROR_TEXT("ERROR during I2C Transaction\n"));


Suggested change

mp_raise_RuntimeError(MP_ERROR_TEXT("ERROR during I2C Transaction\n"));

return MP_EIO;

dhalbert · 2025-06-12T17:36:00Z

ports/analog/common-hal/busio/I2C.c

+    };
+    ret = MXC_I2C_MasterTransaction(&wr_rd_req);
+    if (ret) {
+        mp_raise_RuntimeError(MP_ERROR_TEXT("ERROR during I2C Transaction\n"));


Suggested change

mp_raise_RuntimeError(MP_ERROR_TEXT("ERROR during I2C Transaction\n"));

return MP_EIO;

dhalbert · 2025-06-12T17:38:19Z

ports/analog/common-hal/busio/SPI.c

+            1, 0x01, 1000000, spi_pins);
+        MXC_GPIO_SetVSSEL(MXC_GPIO_GET_GPIO(sck->port), MXC_GPIO_VSSEL_VDDIOH, (sck->mask | miso->mask | mosi->mask | MXC_GPIO_PIN_0));
+        if (err) {
+            mp_raise_RuntimeError(MP_ERROR_TEXT("Failed to init SPI.\n"));


Don't add \n at the end -- that's already taken care of. Also don't add periods: that saves space.

In general, for error messages, see if you can reuse a message from locales/circuitpython.pot. That will save space. Note that quite a few messages are parameterized, like Invalid %q, where the %q is an MP_QSTR_something which often is used elsewhere as well.

Here I am reusing an existing message:

Suggested change

mp_raise_RuntimeError(MP_ERROR_TEXT("Failed to init SPI.\n"));

mp_raise_RuntimeError_varg(MP_ERROR_TEXT("%q init failed", MP_QSTR_SPI));

dhalbert · 2025-06-12T18:22:51Z

ports/analog/common-hal/busio/UART.c

+    }
+    // Check for errors from the callback
+    else if (uart_err != E_NO_ERROR) {
+        mp_printf(&mp_sys_stdout_print, "MAX32 ERR: %d\n", uart_err);


debugging printout

dhalbert · 2025-06-12T18:23:56Z

ports/analog/common-hal/busio/UART.c

+    if (isValidBaudrate(baudrate)) {
+        self->baudrate = baudrate;
+    } else {
+        mp_raise_ValueError(MP_ERROR_TEXT("Baudrate invalid. Must be a standard UART baudrate.\n"));


Suggested change

mp_raise_ValueError(MP_ERROR_TEXT("Baudrate invalid. Must be a standard UART baudrate.\n"));

mp_raise_ValueError_varg(MP_ERROR_TEXT("Invalid %q", MP_QSTR_baudrate));

dhalbert · 2025-06-12T18:27:15Z

ports/analog/peripherals/max32690/max32_spi.c

+            return i;
+        }
+    }
+    mp_raise_RuntimeError_varg(MP_ERROR_TEXT("ERR: Unable to find an SPI matching pins... \


Suggested change

mp_raise_RuntimeError_varg(MP_ERROR_TEXT("ERR: Unable to find an SPI matching pins... \

mp_raise_ValueError_varg(MP_ERROR_TEXT("Invalid %q", MP_QSTR_pins);

dhalbert · 2025-06-12T18:29:18Z

ports/analog/peripherals/max32690/max32_i2c.c

+    mp_raise_RuntimeError_varg(MP_ERROR_TEXT("ERR: Unable to find an I2C matching pins...\nSCL: port %d mask %d\nSDA: port %d mask %d\n"),
+        sda->port, sda->mask, scl->port, scl->mask);


Suggested change

mp_raise_RuntimeError_varg(MP_ERROR_TEXT("ERR: Unable to find an I2C matching pins...\nSCL: port %d mask %d\nSDA: port %d mask %d\n"),

sda->port, sda->mask, scl->port, scl->mask);

mp_raise_ValueError_varg(MP_ERROR_TEXT("Invalid %q", MP_QSTR_pins),

dhalbert · 2025-06-12T18:30:00Z

ports/analog/peripherals/max32690/max32_uart.c

+    mp_raise_RuntimeError_varg(MP_ERROR_TEXT("ERR: Unable to find a uart matching pins...\nTX: port %d mask %d\nRX: port %d mask %d\n"),
+        tx->port, tx->mask, rx->port, rx->mask);


Suggested change

mp_raise_RuntimeError_varg(MP_ERROR_TEXT("ERR: Unable to find a uart matching pins...\nTX: port %d mask %d\nRX: port %d mask %d\n"),

tx->port, tx->mask, rx->port, rx->mask);

mp_raise_ValueError_varg(MP_ERROR_TEXT("Invalid %q", MP_QSTR_pins),

Brandon-Hurst and others added 23 commits June 10, 2025 10:52

Setup files for busio

5052177

Add default build for analog ports for apard32690 board.

0220236

Fixed most UART write issues.

8848d43

- Graceful recovery from timeouts added - Remaining issue still exists where a timeout occurs after a while

Fix issues with UART reads and unreliable UART writes.

872e81c

- No ISR for UART writes, but uses timeouts - Reads use ISRs, but also incorporate timeouts

Add pre-commit changes to UART

d47b882

- Formatting & codespell fixes from pre-commit

Resolve UART ISR naming issues

68d8daa

- Call NVIC_SetRAM in supervisor/port.c to move NVIC table to RAM, enabling ISR RAM remapping. - Rename UART ISR to be generic for any UART IRQn. - Remove background led writes from background.c.

Add BUSIO.I2C and MAX32690 I2C structure

edf069d

- Data structure and constructor for I2C (tested) - Lock and probing functions complete and tested TODO: Implement I2C Write, Read, Wr/Rd Signed-off-by: Brandon-Hurst <[email protected]>

Add hardware mapping for BUSIO.SPI for MAX32690

6967949

Currently coupled a bit to APARD32690-SL board. Will refactor after testing BUSIO.SPI Signed-off-by: Brandon-Hurst <[email protected]>

Add complete BUSIO driver structure for SPI & I2C.

a81ea5e

TODO: - Figure out assigning CS Pins for SPI - Test & Debug SPI / I2C Signed-off-by: Brandon-Hurst <[email protected]>

Add call to MXC_DelayHandler in SysTick ISR

ddd4cf6

Signed-off-by: Brandon-Hurst <[email protected]>

Corrected I2C & SPI. Tested with example scripts; works with real per…

32c6b3e

…ipherals. Signed-off-by: Brandon-Hurst <[email protected]>

Add extra I2C options for MAX32690 non-TQFN packages

88099be

Also reformatted pinmaps for SPI/I2C/UART on MAX32690 Signed-off-by: Brandon Hurst <[email protected]>

Clean up MAX32 BUSIO drivers

5cf0305

- Fixed errors with peripheral bus hardware descriptions in MAX32690 "peripherals/" - Resolved all FIXME comments - Removed unused ringbuf API from common-hal/busio/UART.c Signed-off-by: Brandon Hurst <[email protected]>

Cleanup copy-paste comments in MAX32 busio files

deda980

Signed-off-by: Brandon Hurst <[email protected]>

Correct ringbuffer code for ports/analog BUSIO

0f9ea29

- Add correct ringbuffer handling code to ports/analog/common-hal/UART.c Signed-off-by: Brandon Hurst <[email protected]>

Update jlink script for ports/analog

a305ece

Signed-off-by: Brandon Hurst <[email protected]>

Refactor ports/analog/common-hal/busio i2c probe function.

cbbf34d

- Used direct hardware values to rely on common HW implementation - Accounted for TX Lockout conditions in Transmit FIFO causing errors Signed-off-by: Brandon Hurst <[email protected]>

Expand command in ports/analog/tools/flash_max32.jlink for clarity.

c3ea182

Signed-off-by: Brandon Hurst <[email protected]>

Fix i2c scan bug with ports/analog/ BUSIO.

db95dd0

- Probe function caused infinite loops / unreliable ACK values - Replaced with probe-function with low-level routines Signed-off-by: Brandon Hurst <[email protected]>

Add translations for ports/analog/busio

9b8e08f

Signed-off-by: Brandon Hurst <[email protected]>

Merge branch 'main' into ports/analog/add-busio

363e310

dhalbert requested changes Jun 12, 2025

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Add busio support for ADI MAX32xxx port #10413

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Brandon-Hurst commented Jun 10, 2025 •

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	mp_raise_RuntimeError(MP_ERROR_TEXT("ERROR during I2C Transaction\n"));
	return MP_EIO;

	mp_raise_RuntimeError(MP_ERROR_TEXT("Failed to init SPI.\n"));
	mp_raise_RuntimeError_varg(MP_ERROR_TEXT("%q init failed", MP_QSTR_SPI));

	mp_raise_ValueError(MP_ERROR_TEXT("Baudrate invalid. Must be a standard UART baudrate.\n"));
	mp_raise_ValueError_varg(MP_ERROR_TEXT("Invalid %q", MP_QSTR_baudrate));

		mp_raise_RuntimeError_varg(MP_ERROR_TEXT("ERR: Unable to find an I2C matching pins...\nSCL: port %d mask %d\nSDA: port %d mask %d\n"),
		sda->port, sda->mask, scl->port, scl->mask);

		mp_raise_RuntimeError_varg(MP_ERROR_TEXT("ERR: Unable to find a uart matching pins...\nTX: port %d mask %d\nRX: port %d mask %d\n"),
		tx->port, tx->mask, rx->port, rx->mask);

Add busio support for ADI MAX32xxx port #10413

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Brandon-Hurst commented Jun 10, 2025 •

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