cpuid.c
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/*
* Copyright (C) 2015 <nqdinhddt@gmail.com>
*
* This file is subject to the terms and conditions of the GNU Lesser
* General Public License v2.1. See the file LICENSE in the top level
* directory for more details.
*/
/**
* @addtogroup cpu_sam3
* @{
*
* @file
* @brief Low-level CPUID driver implementation
*
* @author Dinh Nguyen <nqdinhddt@gmail.com>
*
* @}
*/
#include <stdint.h>
#include <string.h>
#include "periph/cpuid.h"
#define EFC_FCMD_STUI 0x0E /* Start unique ID */
#define EFC_FCMD_SPUI 0x0F /* Stop unique ID */
#define EFC_KEY 0x5A
/* During the sequence, the software can not run out of Flash */
__attribute__ ((section (".ramfunc")))
void cpuid_get(void *id)
{
uint32_t cpuid[4]; /* 128 bits sam3 unique indentifier */
/*
Reading SAM3 Unique Identifier process (P 19.3.3.8):
- Send the Start Read unique Identifier command (STUI) by writing the Flash Command Register with the
STUI command.
- When the Unique Identifier is ready to be read, the FRDY bit in the Flash Programming Status Register
(EEFC_FSR) falls
- The Unique Identifier is located in the first 128 bits of the Flash memory mapping. So, at the address
0x400000-0x40008F.
- To stop the Unique Identifier mode, the user needs to send the Stop Read unique Identifier command (SPUI)
by writing the Flash Command Register with the SPUI command.
- When the Stop read Unique Identifier command (SPUI) has been performed, the FRDY bit in the Flash
Programming Status Register (EEFC_FSR) rises. If an interrupt was enabled by setting the FRDY bit in
EEFC_FMR, the interrupt line of the NVIC is activated.
*/
/* Send STUI */
EFC1->EEFC_FCR = EEFC_FCR_FKEY(EFC_KEY) | EFC_FCMD_STUI;
/* Wait for FRDY bit falls */
while (EFC1->EEFC_FSR & EEFC_FSR_FRDY) {}
/* Read UID */
cpuid[0] = *(uint32_t *)IFLASH1_ADDR;
cpuid[1] = *(uint32_t *)(IFLASH1_ADDR + 4);
cpuid[2] = *(uint32_t *)(IFLASH1_ADDR + 8);
cpuid[3] = *(uint32_t *)(IFLASH1_ADDR + 12);
/* Send SPUI */
EFC1->EEFC_FCR = EEFC_FCR_FKEY(EFC_KEY) | EFC_FCMD_SPUI ;
/* Wait for FRDY bit rises. */
while (0 == (EFC1->EEFC_FSR & EEFC_FSR_FRDY)) {}
memcpy(id, (void*)cpuid, CPUID_LEN);
}