MCI UHS-I Tuning

Host-controller tuning operations and results. More...

Macros
#define	ARM_MCI_UHS_TUNING_ABORT   (0x00UL)
	Abort or reset the sampling-clock tuning operation.
#define	ARM_MCI_UHS_TUNING_START   (0x01UL)
	Start initial sampling-clock tuning operation.
#define	ARM_MCI_UHS_RETUNING_START   (0x02UL)
	Start sampling-clock re-tuning during normal operation.
#define	ARM_MCI_UHS_TUNING_DONE   (0)
	Tuning completed successfully.
#define	ARM_MCI_UHS_TUNING_CONTINUE   (1)
	Another tuning-block is required.
#define	ARM_MCI_UHS_TUNING_ERROR   (-1)
	Tuning failed.

Description

Host-controller tuning operations and results.

Call ARM_MCI_Control with control = ARM_MCI_UHS_TUNING_OPERATION. Set arg to one of the phase codes ARM_MCI_UHS_TUNING_ABORT, ARM_MCI_UHS_TUNING_START, or ARM_MCI_UHS_RETUNING_START.

These operations return an execution status, call ARM_MCI_Control with control = ARM_MCI_UHS_TUNING_RESULT and check returned value against ARM_MCI_UHS_TUNING_DONE, ARM_MCI_UHS_TUNING_CONTINUE, or ARM_MCI_UHS_TUNING_ERROR.

UHS-I tuning is performed iteratively until a valid sampling point is found or an error occurs.

Use this order of commands:

1. Start tuning operation using ARM_MCI_UHS_TUNING_OPERATION with ARM_MCI_UHS_TUNING_START
2. Transfer tuning block
3. Inspect the result using ARM_MCI_UHS_TUNING_RESULT

Repeat steps 2 and 3 until the tuning result is ARM_MCI_UHS_TUNING_DONE or an error occurs.

Note

A data CRC error may identify an invalid sampling point and shall not be reported through the ordinary transfer-error event.

Example:

volatile uint32_t MCI_Events;
 
void MCI_SignalEvent_Callback (uint32_t event) {
  // Save current event
  MCI_Events |= event;
}
 
// Tune Sampling Clock
void mci_tune_sampling_clock(void) {
  int32_t status;
  uint8_t buf[64U];
  uint32_t step = 40U;
  uint32_t r1 = 0U;
 
  // Start tuning operation
  if (MCIdrv->Control(ARM_MCI_UHS_TUNING_OPERATION, ARM_MCI_UHS_TUNING_START) != ARM_DRIVER_OK) {
    return;
  }
 
  while(step--) {
    // Setup transfer
    status = MCIdrv->SetupTransfer(buf, 1U, 64U, ARM_MCI_TRANSFER_READ|ARM_MCI_TRANSFER_BLOCK);
    if (status != ARM_DRIVER_OK) {
      break;
    }
 
    // Clear previous events
    MCI_Events = 0;
 
    // Transfer tuning block
    status = MCIdrv->SendCommand(19, 0U, ARM_MCI_RESPONSE_SHORT|ARM_MCI_RESPONSE_CRC|ARM_MCI_TRANSFER_DATA, &r1);
    if (status == ARM_DRIVER_OK) {
      // Wait for event
      while ((MCI_Events & ARM_MCI_EVENT_TRANSFER_COMPLETE) == 0U);
 
      // Check the tuning result
      status = MCIdrv->Control(ARM_MCI_UHS_TUNING_RESULT, 0U);
 
      if (status == ARM_MCI_UHS_TUNING_DONE) {
        // Tuning completed successfully
        return;
      }
      if (status == ARM_MCI_UHS_TUNING_ERROR) {
        // Tuning error occurred
        break;
      }
    }
  }
  // Tuning failed
  MCIdrv->Control(ARM_MCI_UHS_TUNING_OPERATION, ARM_MCI_UHS_TUNING_ABORT);
}

Macro Definition Documentation

ARM_MCI_UHS_TUNING_ABORT

#define ARM_MCI_UHS_TUNING_ABORT   (0x00UL)

Abort or reset the sampling-clock tuning operation.

Stop any active data transfer and reset the tuning configuration.

ARM_MCI_UHS_TUNING_START

#define ARM_MCI_UHS_TUNING_START   (0x01UL)

Start initial sampling-clock tuning operation.

This operation initializes a new sampling-clock search.

ARM_MCI_UHS_RETUNING_START

#define ARM_MCI_UHS_RETUNING_START   (0x02UL)

Start sampling-clock re-tuning during normal operation.

After initial tuning, re-tuning may be required during normal operation, after ARM_MCI_EVENT_RETUNING_REQUEST. Re-tuning ensures that the sampling point remains optimal.

ARM_MCI_UHS_TUNING_DONE

#define ARM_MCI_UHS_TUNING_DONE   (0)

Tuning completed successfully.

A valid sampling setting has been selected and applied. No further tuning block is required for this search.

ARM_MCI_UHS_TUNING_CONTINUE

#define ARM_MCI_UHS_TUNING_CONTINUE   (1)

Another tuning-block is required.

The search has not completed, and another iteration is required.

ARM_MCI_UHS_TUNING_ERROR

#define ARM_MCI_UHS_TUNING_ERROR   (-1)

Tuning failed.

No usable result is available from this search. Stop the tuning loop and perform abort/recovery.

This return value differs from ARM_MCI_EVENT_TUNING_ERROR. That event reports a sampling-circuit failure during normal operation.