MAX30102 Sensor Stalls After First Reading on MAX78000FTHR

[aansrajpoot]

Hi Team,

I hope you're doing well.
I’ve successfully integrated the MPU6050 sensor with the MAX78000FTHR board and verified continuous data acquisition.
Now, I'm working on interfacing the MAX30102 heart rate sensor with the same board. The sensor initializes correctly, and I am able to read the first set of IR and RED values successfully. However, after the initial reading, the code stalls, and no further data is retrieved.
I’ve verified the I2C setup and FIFO read logic, and I suspect the issue might be related to interrupt handling or I2C buffering, but I haven’t been able to resolve it.
Could you please help me debug this issue or guide me toward any working examples or suggestions?
Any assistance would be greatly appreciated.
Thank you!

-Below is the attached code file.
MAX30201.txt

With the above code, I am getting this output: It gets stuck at uint8_t int_status when the second iteration comes.
System Init
Checking MAX30102...
MAX30102 detected! PART ID = 0x15
Configuring MAX30102...

start
start1
start2
FIFO read complete with ret = 0
IR: 34, RED: 34
Done

start

[sihyung-maxim]

Hi - it's interesting that the code halts at line 148 at uint8_t int_status. Could you confirm which fault exception is raised when you encounter the stall?

[aansrajpoot]

Hi - it's interesting that the code halts at line 148 at uint8_t int_status. Could you confirm which fault exception is raised when you encounter the stall?

Hi,
Thanks for your reply. I hope you're doing well.

I'm currently working on interfacing the MAX30102 heart rate sensor with the MAX78000FTHR board. The sensor is successfully detected via I2C, and the initialization sequence seems to complete correctly. However, I'm encountering a runtime issue during the periodic sampling phase, which causes the firmware to stall unexpectedly.

Below is the exact output observed on the serial terminal:
System Init
Checking MAX30102...
MAX30102 detected! PART ID = 0x15
Initializing MAX30102...
MAX30102 Initialized.
Sampling every 1s...
Starting sample...
Reading INT_STATUS...
Reading INT_STATUS (0x00)...
Reading INT_STATUS2 (0x01)...
INT_STATUS = 0x40, INT_STATUS2 = 0x00
Reading FIFO...
Sample - IR: 102538, RED: 153163
Sample done. Waiting 1s...
Starting sample...
Reading INT_STATUS...
Reading INT_STATUS (0x00)...

What’s Working:
The board successfully initializes system clocks and the I2C peripheral.
The MAX30102 is detected and responds correctly with PART ID = 0x15.
Initialization of sensor registers completes without error.
The first sample is read successfully from the FIFO (INT_STATUS = 0x40 confirms data ready).

The Issue:
After the first sample is read, the second iteration of the sampling loop begins but gets stuck during the second read of INT_STATUS (0x00). It prints "Reading INT_STATUS (0x00)...", but does not proceed to read INT_STATUS2 or the FIFO.
This strongly suggests that the code is stuck during the I2C read transaction from register 0x00, and the MXC_I2C_MasterTransaction() function is not returning.

Additional Notes:
I added retry logic and timeout protection using a timer, but the stall still occurs at the same point.
The issue persists regardless of whether a finger is on the sensor or not.
I also experimented with different USB cables and confirmed a stable power supply.

My Suspected Causes:
The MAX30102 interrupt flag (0x40) might not be getting cleared even after the FIFO read.
A low-level I2C state machine issue might be causing a hang inside the peripheral driver.
Possibly a stuck interrupt or FIFO pointer state in the MAX30102 that prevents subsequent data from being readable.

Would you be able to advise based on this behavior? I’d also appreciate it if you could take a quick look at the I2C communication flow or suggest a more robust way to clear the interrupt and reset the I2C peripheral if this happens.

I hope you'd like to see the full code or specific I2C trace logs — I’m happy to provide those as well.
Please view the attached file.

MAX30201_1.txt

Thank you for your time and assistance.

[aansrajpoot]

Hi, Thanks for your reply. I hope you're doing well. I'm currently working on interfacing the MAX30102 heart rate sensor with the MAX78000FTHR board. The sensor is successfully detected via I2C, and the initialization sequence seems to complete correctly. However, I'm encountering a runtime issue during the periodic sampling phase, which causes the firmware to stall unexpectedly. Below is the exact output observed on the serial terminal: System Init Checking MAX30102... MAX30102 detected! PART ID = 0x15 Initializing MAX30102... MAX30102 Initialized. Sampling every 1s... Starting sample... Reading INT_STATUS... Reading INT_STATUS (0x00)... Reading INT_STATUS2 (0x01)... INT_STATUS = 0x40, INT_STATUS2 = 0x00 Reading FIFO... Sample - IR: 102538, RED: 153163 Sample done. Waiting 1s... Starting sample... Reading INT_STATUS... Reading INT_STATUS (0x00)... What’s Working: The board successfully initializes system clocks and the I2C peripheral. The MAX30102 is detected and responds correctly with PART ID = 0x15. Initialization of sensor registers completes without error. The first sample is read successfully from the FIFO (INT_STATUS = 0x40 confirms data ready). The Issue: After the first sample is read, the second iteration of the sampling loop begins but gets stuck during the second read of INT_STATUS (0x00). It prints "Reading INT_STATUS (0x00)...", but does not proceed to read INT_STATUS2 or the FIFO. This strongly suggests that the code is stuck during the I2C read transaction from register 0x00, and the MXC_I2C_MasterTransaction() function is not returning. Additional Notes: I added retry logic and timeout protection using a timer, but the stall still occurs at the same point. The issue persists regardless of whether a finger is on the sensor or not. I also experimented with different USB cables and confirmed a stable power supply. My Suspected Causes: The MAX30102 interrupt flag (0x40) might not be getting cleared even after the FIFO read. A low-level I2C state machine issue might be causing a hang inside the peripheral driver. Possibly a stuck interrupt or FIFO pointer state in the MAX30102 that prevents subsequent data from being readable. Would you be able to advise based on this behavior? I’d also appreciate it if you could take a quick look at the I2C communication flow or suggest a more robust way to clear the interrupt and reset the I2C peripheral if this happens. Let me know if you'd like to see the full code or specific I2C trace logs — I’m happy to provide those as well. Please view the attached file. Thank you for your time and assistance. Regards: Aans

On Mon, Jul 14, 2025 at 7:46 PM Sihyung Woo ***@***.***> wrote: *sihyung-maxim* left a comment (analogdevicesinc/msdk#1409) <#1409 (comment)> Hi - it's interesting that the code halts at line 148 at uint8_t int_status. Could you confirm which fault exception is raised when you encounter the stall? — Reply to this email directly, view it on GitHub <#1409 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/ASJ2NM7YYMQYRIJ7CFX4I7D3IO7FDAVCNFSM6AAAAACBII3AMSVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZTANRZHA4DENBVGA> . You are receiving this because you authored the thread.Message ID: ***@***.***>

#include "mxc.h" #include "board.h" #include "gpio.h" #include "i2c.h" #include "stdio.h" #define I2C_MASTER MXC_I2C1 #define MAX30102_ADDR 0x57 #define REG_PART_ID 0xFF #define REG_FIFO_DATA 0x07 #define REG_FIFO_WR_PTR 0x04 #define REG_FIFO_RD_PTR 0x06 #define REG_OVF_COUNTER 0x05 #define REG_INT_STATUS 0x00 #define I2C_IS_BUSY(i2c) ((i2c->status & MXC_F_I2C_STATUS_BUSY) != 0) void delay_ms(int ms) { MXC_Delay(MXC_DELAY_MSEC(ms)); } void clear_i2c_flags(void) { unsigned int flags0 = 0, flags1 = 0; MXC_I2C_GetFlags(I2C_MASTER, &flags0, &flags1); MXC_I2C_ClearFlags(I2C_MASTER, flags0, flags1); } int i2c_transaction_timeout(mxc_i2c_req_t* req, uint32_t timeout_ms) { uint32_t start = MXC_TMR0->cnt; uint32_t timeout_ticks = (SystemCoreClock / 1000) * timeout_ms; int ret; do { ret = MXC_I2C_MasterTransaction(req); if (ret == E_NO_ERROR) return ret; printf("Retrying I2C, ret = %d...\n", ret); } while ((MXC_TMR0->cnt - start) < timeout_ticks); printf("ERROR: I2C transaction timed out after %ums\n", timeout_ms); return -1; } int max30102_write_reg(uint8_t reg, uint8_t value) { uint8_t data[2] = {reg, value}; mxc_i2c_req_t req = { .i2c = I2C_MASTER, .addr = MAX30102_ADDR, .tx_buf = data, .tx_len = 2, .rx_buf = NULL, .rx_len = 0, .restart = 0, .callback = NULL }; clear_i2c_flags(); MXC_I2C_ClearRXFIFO(I2C_MASTER); MXC_I2C_ClearTXFIFO(I2C_MASTER); delay_ms(5); return i2c_transaction_timeout(&req, 100); } int max30102_read_reg(uint8_t reg, uint8_t* value) { mxc_i2c_req_t req = { .i2c = I2C_MASTER, .addr = MAX30102_ADDR, .tx_buf = &reg, .tx_len = 1, .rx_buf = value, .rx_len = 1, .restart = 1, .callback = NULL }; clear_i2c_flags(); MXC_I2C_ClearRXFIFO(I2C_MASTER); MXC_I2C_ClearTXFIFO(I2C_MASTER); delay_ms(5); return i2c_transaction_timeout(&req, 100); } int max30102_init(void) { printf("Initializing MAX30102...\n"); // Reset if (max30102_write_reg(0x09, 0x40) != E_NO_ERROR) { printf("ERROR: Reset failed (REG 0x09, VAL 0x40)\n"); return -1; } delay_ms(100); // Interrupt enable: A_FULL_EN=1, PPG_RDY_EN=1 if (max30102_write_reg(0x02, 0xC0) != E_NO_ERROR) { printf("ERROR: Interrupt enable failed (REG 0x02, VAL 0xC0)\n"); return -1; } // FIFO config: sample avg = 4, rollover enabled, almost full = 17 if (max30102_write_reg(0x08, 0x4F) != E_NO_ERROR) { printf("ERROR: FIFO config failed (REG 0x08, VAL 0x4F)\n"); return -1; } // Mode config: SpO2 mode if (max30102_write_reg(0x09, 0x03) != E_NO_ERROR) { printf("ERROR: Mode config failed (REG 0x09, VAL 0x03)\n"); return -1; } // SpO2 config: 100 Hz, 411us, 18-bit if (max30102_write_reg(0x0A, 0x27) != E_NO_ERROR) { printf("ERROR: SpO2 config failed (REG 0x0A, VAL 0x27)\n"); return -1; } // LED1 pulse amplitude (RED) if (max30102_write_reg(0x0C, 0x24) != E_NO_ERROR) { printf("ERROR: LED1 (RED) amplitude config failed (REG 0x0C, VAL 0x24)\n"); return -1; } // LED2 pulse amplitude (IR) if (max30102_write_reg(0x0D, 0x24) != E_NO_ERROR) { printf("ERROR: LED2 (IR) amplitude config failed (REG 0x0D, VAL 0x24)\n"); return -1; } // Multi-LED mode control: Slot 1 = RED, Slot 2 = IR if (max30102_write_reg(0x11, 0x21) != E_NO_ERROR) { printf("ERROR: Multi-LED slot config failed (REG 0x11, VAL 0x21)\n"); return -1; } // Clear FIFO pointers if (max30102_write_reg(0x04, 0x00) != E_NO_ERROR) { printf("ERROR: FIFO_WR_PTR reset failed (REG 0x04, VAL 0x00)\n"); return -1; } if (max30102_write_reg(0x05, 0x00) != E_NO_ERROR) { printf("ERROR: OVF_COUNTER reset failed (REG 0x05, VAL 0x00)\n"); return -1; } if (max30102_write_reg(0x06, 0x00) != E_NO_ERROR) { printf("ERROR: FIFO_RD_PTR reset failed (REG 0x06, VAL 0x00)\n"); return -1; } printf("MAX30102 Initialized.\n"); return 0; } void read_max30102_sample(void) { uint8_t int_status = 0, int_status2 = 0; uint8_t fifo_data[6]; uint8_t reg = REG_FIFO_DATA; uint32_t ir = 0, red = 0; printf("Reading INT_STATUS...\n"); // Read interrupt status 1 printf("Reading INT_STATUS (0x00)...\n"); if (max30102_read_reg(0x00, &int_status) != E_NO_ERROR) { printf("ERROR: Failed to read INT_STATUS1. Trying to reset sensor.\n"); max30102_init(); // Soft reset if stuck return; } // Read interrupt status 2 printf("Reading INT_STATUS2 (0x01)...\n"); if (max30102_read_reg(0x01, &int_status2) != E_NO_ERROR) { printf("ERROR: Failed to read INT_STATUS2. Trying to reset sensor.\n"); max30102_init(); // Soft reset return; } printf("INT_STATUS = 0x%02X, INT_STATUS2 = 0x%02X\n", int_status, int_status2); // If no new sample, still read FIFO to avoid sensor freeze if (!(int_status & 0x40)) { printf("No new data in FIFO, but reading FIFO to keep sensor happy...\n"); } else { printf("Reading FIFO...\n"); } mxc_i2c_req_t req = { .i2c = I2C_MASTER, .addr = MAX30102_ADDR, .tx_buf = &reg, .tx_len = 1, .rx_buf = fifo_data, .rx_len = 6, .restart = 1, .callback = NULL }; int ret = i2c_transaction_timeout(&req, 100); if (ret != E_NO_ERROR) { printf("ERROR: Failed to read FIFO, ret = %d. Resetting sensor.\n", ret); max30102_init(); return; } ir = ((uint32_t)(fifo_data[0] & 0x03) << 16) | (fifo_data[1] << 8) | fifo_data[2]; red = ((uint32_t)(fifo_data[3] & 0x03) << 16) | (fifo_data[4] << 8) | fifo_data[5]; printf("Sample - IR: %lu, RED: %lu\n", ir, red); } int main(void) { uint8_t part_id; MXC_ICC_Enable(MXC_ICC0); MXC_SYS_Clock_Select(MXC_SYS_CLOCK_IPO); SystemCoreClockUpdate(); printf("System Init\n"); MXC_TMR_Init(MXC_TMR0, TMR_PRES_1, NULL); MXC_TMR_Start(MXC_TMR0); MXC_SYS_ClockEnable(MXC_SYS_PERIPH_CLOCK_I2C1); MXC_GPIO_Config(&gpio_cfg_i2c1); if (MXC_I2C_Init(I2C_MASTER, 1, 0) != E_NO_ERROR) { printf("ERROR: I2C Init failed\n"); return -1; } MXC_I2C_SetFrequency(I2C_MASTER, 400000); printf("Checking MAX30102...\n"); if (max30102_read_reg(REG_PART_ID, &part_id) != E_NO_ERROR) { printf("ERROR: Failed to read PART ID\n"); return -1; } printf("MAX30102 detected! PART ID = 0x%02X\n", part_id); if (max30102_init() != 0) { printf("ERROR: Sensor initialization failed\n"); return -1; } printf("Sampling every 1s...\n"); while (1) { printf("Starting sample...\n"); read_max30102_sample(); printf("Sample done. Waiting 1s...\n"); delay_ms(1000); } }

[aansrajpoot]

Hi, Here you can view the logs: got these logs: Open On-Chip Debugger (Analog Devices 0.12.0-1.0.0-7) OpenOCD 0.12.0 (2023-09-27-07:53) Licensed under GNU GPL v2 Report bugs to ***@***.***> Started by GNU MCU Eclipse Info : Listening on port 6666 for tcl connections Info : Listening on port 4444 for telnet connections Info : CMSIS-DAP: SWD supported Info : CMSIS-DAP: Atomic commands supported Info : CMSIS-DAP: Test domain timer supported Info : CMSIS-DAP: FW Version = 0256 Info : CMSIS-DAP: Serial# = 044417011fe28a6500000000000000000000000097969906 Info : CMSIS-DAP: Interface Initialised (SWD) Info : SWCLK/TCK = 1 SWDIO/TMS = 1 TDI = 0 TDO = 0 nTRST = 0 nRESET = 1 Info : CMSIS-DAP: Interface ready Info : clock speed 2000 kHz Info : SWD DPIDR 0x2ba01477 Info : [max32xxx.cpu] Cortex-M4 r0p1 processor detected Info : [max32xxx.cpu] target has 6 breakpoints, 4 watchpoints Info : starting gdb server for max32xxx.cpu on 3333 Info : Listening on port 3333 for gdb connections Info : accepting 'gdb' connection on tcp/3333 [max32xxx.cpu] halted due to debug-request, current mode: Thread xPSR: 0x210f0000 pc: 0x10001a9e msp: 0x2001ff38 Warn : Prefer GDB command "target extended-remote :3333" instead of "target remote :3333" Info : SWD DPIDR 0x2ba01477 [max32xxx.cpu] halted due to debug-request, current mode: Thread xPSR: 0x81000000 pc: 0x00002124 msp: 0x20003ff0 Warn : No RTOS could be auto-detected! Warn : No RTOS could be auto-detected! Info : SWD DPIDR 0x2ba01477 [max32xxx.cpu] halted due to debug-request, current mode: Thread xPSR: 0x81000000 pc: 0x00002124 msp: 0x20003ff0 Info : SWD DPIDR 0x2ba01477 [max32xxx.cpu] halted due to debug-request, current mode: Thread xPSR: 0x81000000 pc: 0x00002124 msp: 0x20003ff0 On Tue, Jul 15, 2025 at 11:44 PM Ans Rajpoot ***@***.***> wrote:

Hi, Thanks for your reply. I hope you're doing well. I'm currently working on interfacing the MAX30102 heart rate sensor with the MAX78000FTHR board. The sensor is successfully detected via I2C, and the initialization sequence seems to complete correctly. However, I'm encountering a runtime issue during the periodic sampling phase, which causes the firmware to stall unexpectedly. Below is the exact output observed on the serial terminal: System Init Checking MAX30102... MAX30102 detected! PART ID = 0x15 Initializing MAX30102... MAX30102 Initialized. Sampling every 1s... Starting sample... Reading INT_STATUS... Reading INT_STATUS (0x00)... Reading INT_STATUS2 (0x01)... INT_STATUS = 0x40, INT_STATUS2 = 0x00 Reading FIFO... Sample - IR: 102538, RED: 153163 Sample done. Waiting 1s... Starting sample... Reading INT_STATUS... Reading INT_STATUS (0x00)... What’s Working: The board successfully initializes system clocks and the I2C peripheral. The MAX30102 is detected and responds correctly with PART ID = 0x15. Initialization of sensor registers completes without error. The first sample is read successfully from the FIFO (INT_STATUS = 0x40 confirms data ready). The Issue: After the first sample is read, the second iteration of the sampling loop begins but gets stuck during the second read of INT_STATUS (0x00). It prints "Reading INT_STATUS (0x00)...", but does not proceed to read INT_STATUS2 or the FIFO. This strongly suggests that the code is stuck during the I2C read transaction from register 0x00, and the MXC_I2C_MasterTransaction() function is not returning. Additional Notes: I added retry logic and timeout protection using a timer, but the stall still occurs at the same point. The issue persists regardless of whether a finger is on the sensor or not. I also experimented with different USB cables and confirmed a stable power supply. My Suspected Causes: The MAX30102 interrupt flag (0x40) might not be getting cleared even after the FIFO read. A low-level I2C state machine issue might be causing a hang inside the peripheral driver. Possibly a stuck interrupt or FIFO pointer state in the MAX30102 that prevents subsequent data from being readable. Would you be able to advise based on this behavior? I’d also appreciate it if you could take a quick look at the I2C communication flow or suggest a more robust way to clear the interrupt and reset the I2C peripheral if this happens. Let me know if you'd like to see the full code or specific I2C trace logs — I’m happy to provide those as well. Please view the attached file. Thank you for your time and assistance. Regards: Aans On Mon, Jul 14, 2025 at 7:46 PM Sihyung Woo ***@***.***> wrote: > *sihyung-maxim* left a comment (analogdevicesinc/msdk#1409) > <#1409 (comment)> > > Hi - it's interesting that the code halts at line 148 at uint8_t > int_status. Could you confirm which fault exception is raised when you > encounter the stall? > > — > Reply to this email directly, view it on GitHub > <#1409 (comment)>, > or unsubscribe > <https://github.com/notifications/unsubscribe-auth/ASJ2NM7YYMQYRIJ7CFX4I7D3IO7FDAVCNFSM6AAAAACBII3AMSVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZTANRZHA4DENBVGA> > . > You are receiving this because you authored the thread.Message ID: > ***@***.***> >

#include "mxc.h" #include "board.h" #include "gpio.h" #include "i2c.h" #include "stdio.h" #define I2C_MASTER MXC_I2C1 #define MAX30102_ADDR 0x57 #define REG_PART_ID 0xFF #define REG_FIFO_DATA 0x07 #define REG_FIFO_WR_PTR 0x04 #define REG_FIFO_RD_PTR 0x06 #define REG_OVF_COUNTER 0x05 #define REG_INT_STATUS 0x00 #define I2C_IS_BUSY(i2c) ((i2c->status & MXC_F_I2C_STATUS_BUSY) != 0) void delay_ms(int ms) { MXC_Delay(MXC_DELAY_MSEC(ms)); } void clear_i2c_flags(void) { unsigned int flags0 = 0, flags1 = 0; MXC_I2C_GetFlags(I2C_MASTER, &flags0, &flags1); MXC_I2C_ClearFlags(I2C_MASTER, flags0, flags1); } int i2c_transaction_timeout(mxc_i2c_req_t* req, uint32_t timeout_ms) { uint32_t start = MXC_TMR0->cnt; uint32_t timeout_ticks = (SystemCoreClock / 1000) * timeout_ms; int ret; do { ret = MXC_I2C_MasterTransaction(req); if (ret == E_NO_ERROR) return ret; printf("Retrying I2C, ret = %d...\n", ret); } while ((MXC_TMR0->cnt - start) < timeout_ticks); printf("ERROR: I2C transaction timed out after %ums\n", timeout_ms); return -1; } int max30102_write_reg(uint8_t reg, uint8_t value) { uint8_t data[2] = {reg, value}; mxc_i2c_req_t req = { .i2c = I2C_MASTER, .addr = MAX30102_ADDR, .tx_buf = data, .tx_len = 2, .rx_buf = NULL, .rx_len = 0, .restart = 0, .callback = NULL }; clear_i2c_flags(); MXC_I2C_ClearRXFIFO(I2C_MASTER); MXC_I2C_ClearTXFIFO(I2C_MASTER); delay_ms(5); return i2c_transaction_timeout(&req, 100); } int max30102_read_reg(uint8_t reg, uint8_t* value) { mxc_i2c_req_t req = { .i2c = I2C_MASTER, .addr = MAX30102_ADDR, .tx_buf = &reg, .tx_len = 1, .rx_buf = value, .rx_len = 1, .restart = 1, .callback = NULL }; clear_i2c_flags(); MXC_I2C_ClearRXFIFO(I2C_MASTER); MXC_I2C_ClearTXFIFO(I2C_MASTER); delay_ms(5); return i2c_transaction_timeout(&req, 100); } int max30102_init(void) { printf("Initializing MAX30102...\n"); // Reset if (max30102_write_reg(0x09, 0x40) != E_NO_ERROR) { printf("ERROR: Reset failed (REG 0x09, VAL 0x40)\n"); return -1; } delay_ms(100); // Interrupt enable: A_FULL_EN=1, PPG_RDY_EN=1 if (max30102_write_reg(0x02, 0xC0) != E_NO_ERROR) { printf("ERROR: Interrupt enable failed (REG 0x02, VAL 0xC0)\n"); return -1; } // FIFO config: sample avg = 4, rollover enabled, almost full = 17 if (max30102_write_reg(0x08, 0x4F) != E_NO_ERROR) { printf("ERROR: FIFO config failed (REG 0x08, VAL 0x4F)\n"); return -1; } // Mode config: SpO2 mode if (max30102_write_reg(0x09, 0x03) != E_NO_ERROR) { printf("ERROR: Mode config failed (REG 0x09, VAL 0x03)\n"); return -1; } // SpO2 config: 100 Hz, 411us, 18-bit if (max30102_write_reg(0x0A, 0x27) != E_NO_ERROR) { printf("ERROR: SpO2 config failed (REG 0x0A, VAL 0x27)\n"); return -1; } // LED1 pulse amplitude (RED) if (max30102_write_reg(0x0C, 0x24) != E_NO_ERROR) { printf("ERROR: LED1 (RED) amplitude config failed (REG 0x0C, VAL 0x24)\n"); return -1; } // LED2 pulse amplitude (IR) if (max30102_write_reg(0x0D, 0x24) != E_NO_ERROR) { printf("ERROR: LED2 (IR) amplitude config failed (REG 0x0D, VAL 0x24)\n"); return -1; } // Multi-LED mode control: Slot 1 = RED, Slot 2 = IR if (max30102_write_reg(0x11, 0x21) != E_NO_ERROR) { printf("ERROR: Multi-LED slot config failed (REG 0x11, VAL 0x21)\n"); return -1; } // Clear FIFO pointers if (max30102_write_reg(0x04, 0x00) != E_NO_ERROR) { printf("ERROR: FIFO_WR_PTR reset failed (REG 0x04, VAL 0x00)\n"); return -1; } if (max30102_write_reg(0x05, 0x00) != E_NO_ERROR) { printf("ERROR: OVF_COUNTER reset failed (REG 0x05, VAL 0x00)\n"); return -1; } if (max30102_write_reg(0x06, 0x00) != E_NO_ERROR) { printf("ERROR: FIFO_RD_PTR reset failed (REG 0x06, VAL 0x00)\n"); return -1; } printf("MAX30102 Initialized.\n"); return 0; } void read_max30102_sample(void) { uint8_t int_status = 0, int_status2 = 0; uint8_t fifo_data[6]; uint8_t reg = REG_FIFO_DATA; uint32_t ir = 0, red = 0; printf("Reading INT_STATUS...\n"); // Read interrupt status 1 printf("Reading INT_STATUS (0x00)...\n"); if (max30102_read_reg(0x00, &int_status) != E_NO_ERROR) { printf("ERROR: Failed to read INT_STATUS1. Trying to reset sensor.\n"); max30102_init(); // Soft reset if stuck return; } // Read interrupt status 2 printf("Reading INT_STATUS2 (0x01)...\n"); if (max30102_read_reg(0x01, &int_status2) != E_NO_ERROR) { printf("ERROR: Failed to read INT_STATUS2. Trying to reset sensor.\n"); max30102_init(); // Soft reset return; } printf("INT_STATUS = 0x%02X, INT_STATUS2 = 0x%02X\n", int_status, int_status2); // If no new sample, still read FIFO to avoid sensor freeze if (!(int_status & 0x40)) { printf("No new data in FIFO, but reading FIFO to keep sensor happy...\n"); } else { printf("Reading FIFO...\n"); } mxc_i2c_req_t req = { .i2c = I2C_MASTER, .addr = MAX30102_ADDR, .tx_buf = &reg, .tx_len = 1, .rx_buf = fifo_data, .rx_len = 6, .restart = 1, .callback = NULL }; int ret = i2c_transaction_timeout(&req, 100); if (ret != E_NO_ERROR) { printf("ERROR: Failed to read FIFO, ret = %d. Resetting sensor.\n", ret); max30102_init(); return; } ir = ((uint32_t)(fifo_data[0] & 0x03) << 16) | (fifo_data[1] << 8) | fifo_data[2]; red = ((uint32_t)(fifo_data[3] & 0x03) << 16) | (fifo_data[4] << 8) | fifo_data[5]; printf("Sample - IR: %lu, RED: %lu\n", ir, red); } int main(void) { uint8_t part_id; MXC_ICC_Enable(MXC_ICC0); MXC_SYS_Clock_Select(MXC_SYS_CLOCK_IPO); SystemCoreClockUpdate(); printf("System Init\n"); MXC_TMR_Init(MXC_TMR0, TMR_PRES_1, NULL); MXC_TMR_Start(MXC_TMR0); MXC_SYS_ClockEnable(MXC_SYS_PERIPH_CLOCK_I2C1); MXC_GPIO_Config(&gpio_cfg_i2c1); if (MXC_I2C_Init(I2C_MASTER, 1, 0) != E_NO_ERROR) { printf("ERROR: I2C Init failed\n"); return -1; } MXC_I2C_SetFrequency(I2C_MASTER, 400000); printf("Checking MAX30102...\n"); if (max30102_read_reg(REG_PART_ID, &part_id) != E_NO_ERROR) { printf("ERROR: Failed to read PART ID\n"); return -1; } printf("MAX30102 detected! PART ID = 0x%02X\n", part_id); if (max30102_init() != 0) { printf("ERROR: Sensor initialization failed\n"); return -1; } printf("Sampling every 1s...\n"); while (1) { printf("Starting sample...\n"); read_max30102_sample(); printf("Sample done. Waiting 1s...\n"); delay_ms(1000); } }

[sihyung-maxim]

Hi, sorry for the late response. I ordered a sample board to test your code myself and am waiting for it to arrive.

Nothing in your code is sticking out to me just yet. Could you send a logic analyzer capture of the I2C transaction, and a register dump of the I2C registers before and after the failure point?

[aansrajpoot]

Hi,
I hope you're doing well.
Although I don't currently have access to a logic analyzer, I’ve performed a register dump of the MAX30102 sensor’s I2C registers before and after the failure point using the MAX78000FTHR board.

I’ve attached the code I used along with the console output below. The key point observed is that the INT_STATUS register initially shows 0x40 (indicating new FIFO data available), but immediately after that it changes to 0x00, even though no data has yet been read—suggesting the interrupt flag may be getting cleared unexpectedly or prematurely.

In addition, the overflow counter (REG 0x05) consistently shows 0x01, which triggers the “FIFO Overflow detected” logic—resulting in a FIFO pointer reset. This behavior appears to repeat each second, meaning samples are being acquired, but interrupt handling or data clearing is not stable.
Please have a look and let me know your insights.

output.txt

code.txt