/**
* Copyright (c) 2020 Raspberry Pi (Trading) Ltd.
*
* SPDX-License-Identifier: BSD-3-Clause
*/
#include <stdio.h>
#include "pico/stdlib.h"
#include "pico/bootrom.h"
#include "hardware/structs/otp.h"
int main() {
stdio_init_all();
otp_cmd_t cmd;
int8_t ret;
// Row to write ECC data
uint16_t ecc_row = 0x400;
// Row to write raw data
uint16_t raw_row = 0x410;
// Check rows are empty - else the rest of the tests won't behave as expected
unsigned char initial_data[32] = {0};
cmd.flags = ecc_row;
ret = rom_func_otp_access(initial_data, sizeof(initial_data)/2, cmd);
if (ret) {
printf("ERROR: Initial ECC Row Read failed with error %d\n", ret);
}
cmd.flags = raw_row;
ret = rom_func_otp_access(initial_data+(sizeof(initial_data)/2), sizeof(initial_data)/2, cmd);
if (ret) {
printf("ERROR: Initial Raw Row Read failed with error %d\n", ret);
}
for (int i=0; i < sizeof(initial_data); i++) {
if (initial_data[i] != 0) {
printf("ERROR: This example requires empty OTP rows to run - change the ecc_row and raw_row variables to an empty row and recompile\n");
return 0;
}
}
if (ecc_row) {
// Write an ECC value to OTP - the buffer must have a multiple of 2 length for ECC data
unsigned char ecc_write_data[16] = "Hello from OTP";
cmd.flags = ecc_row | OTP_CMD_ECC_BITS | OTP_CMD_WRITE_BITS;
ret = rom_func_otp_access(ecc_write_data, sizeof(ecc_write_data), cmd);
if (ret) {
printf("ERROR: ECC Write failed with error %d\n", ret);
} else {
printf("ECC Write succeeded\n");
}
// Read it back
unsigned char ecc_read_data[sizeof(ecc_write_data)] = {0};
cmd.flags = ecc_row | OTP_CMD_ECC_BITS;
ret = rom_func_otp_access(ecc_read_data, sizeof(ecc_read_data), cmd);
if (ret) {
printf("ERROR: ECC Read failed with error %d\n", ret);
} else {
printf("ECC Data read is \"%s\"\n", ecc_read_data);
}
// Set some bits, to demonstrate ECC error correction
unsigned char ecc_toggle_buffer[sizeof(ecc_write_data)*2] = {0};
cmd.flags = ecc_row;
ret = rom_func_otp_access(ecc_toggle_buffer, sizeof(ecc_toggle_buffer), cmd);
if (ret) {
printf("ERROR: Raw read of ECC data failed with error %d\n", ret);
} else {
ecc_toggle_buffer[0] = 'x'; // will fail to recover, as flips 2 bits from 'H' (100_1000 -> 111_1000)
ecc_toggle_buffer[24] = 't'; // will recover, as only flips 1 bit from 'T' (101_0100 -> 111_0100)
cmd.flags = ecc_row | OTP_CMD_WRITE_BITS;
ret = rom_func_otp_access(ecc_toggle_buffer, sizeof(ecc_toggle_buffer), cmd);
if (ret) {
printf("ERROR: Raw overwrite of ECC data failed with error %d\n", ret);
} else {
printf("Raw overwrite of ECC data succeeded\n");
}
}
// Read it back
unsigned char ecc_toggled_read_data[sizeof(ecc_write_data)] = {0};
cmd.flags = ecc_row | OTP_CMD_ECC_BITS;
ret = rom_func_otp_access(ecc_toggled_read_data, sizeof(ecc_toggled_read_data), cmd);
if (ret) {
printf("ERROR: ECC Read failed with error %d\n", ret);
} else {
printf("ECC Data read is now \"%s\"\n", ecc_toggled_read_data);
}
// Attempt to write a different ECC value to OTP - should fail
unsigned char ecc_overwrite_data[sizeof(ecc_write_data)] = "hello from otp";
cmd.flags = ecc_row | OTP_CMD_ECC_BITS | OTP_CMD_WRITE_BITS;
ret = rom_func_otp_access(ecc_overwrite_data, sizeof(ecc_overwrite_data), cmd);
if (ret == BOOTROM_ERROR_UNSUPPORTED_MODIFICATION) {
printf("Overwrite of ECC data failed as expected\n");
} else {
printf("ERROR: ");
if (ret) {
printf("Overwrite failed with error %d\n", ret);
} else {
printf("Overwrite succeeded\n");
}
}
}
if (raw_row) {
// Write a raw value to OTP - the buffer must have a multiple of 4 length for raw data
// Each row only holds 24 bits, so every 4th byte isn't written to OTP
unsigned char raw_write_data[20] = "Hel\0lo \0fro\0m O\0TP";
cmd.flags = raw_row | OTP_CMD_WRITE_BITS;
ret = rom_func_otp_access(raw_write_data, sizeof(raw_write_data), cmd);
if (ret) {
printf("ERROR: Raw Write failed with error %d\n", ret);
} else {
printf("Raw Write succeeded\n");
}
// Read it back
unsigned char raw_read_data[sizeof(raw_write_data)] = {0};
cmd.flags = raw_row;
ret = rom_func_otp_access(raw_read_data, sizeof(raw_read_data), cmd);
if (ret) {
printf("ERROR: Raw Read failed with error %d\n", ret);
} else {
// Remove the null bytes
for (int i=0; i < sizeof(raw_read_data)/4; i++) {
memcpy(raw_read_data + i*3, raw_read_data + i*4, 3);
}
printf("Raw Data read is \"%s\"\n", raw_read_data);
}
// Attempt to write a different raw value to OTP - should succeed, provided no bits are cleared
// This can be done by using '~' for even characters, and 'o' for odd ones
unsigned char raw_overwrite_data[sizeof(raw_write_data)] = {0};
for (int i=0; i < sizeof(raw_write_data); i++) {
if (raw_write_data[i]) {
raw_overwrite_data[i] = (raw_write_data[i] % 2) ? 'o' : '~';
} else {
raw_overwrite_data[i] = 0;
}
}
cmd.flags = raw_row | OTP_CMD_WRITE_BITS;
ret = rom_func_otp_access(raw_overwrite_data, sizeof(raw_overwrite_data), cmd);
if (ret) {
printf("ERROR: Raw Overwrite failed with error %d\n", ret);
} else {
printf("Raw Overwrite succeeded\n");
}
// Read it back
unsigned char raw_read_data_again[sizeof(raw_write_data)] = {0};
cmd.flags = raw_row;
ret = rom_func_otp_access(raw_read_data_again, sizeof(raw_read_data_again), cmd);
// Remove the null bytes
for (int i=0; i < sizeof(raw_read_data_again)/4; i++) {
memcpy(raw_read_data_again + i*3, raw_read_data_again + i*4, 3);
}
if (ret) {
printf("ERROR: Raw Read failed with error %d\n", ret);
} else {
printf("Raw Data read is now \"%s\"\n", raw_read_data_again);
}
}
int16_t lock_row = ecc_row ? ecc_row : raw_row;
// Lock the OTP page, to prevent any more reads or writes until the next reset
int page = lock_row / 0x40;
otp_hw->sw_lock[page] = 0xf;
printf("OTP Software Lock Done\n");
// Attempt to read it back again - should fail
unsigned char read_data_locked[8] = {0};
cmd.flags = lock_row | (lock_row == ecc_row ? OTP_CMD_ECC_BITS : 0);
ret = rom_func_otp_access(read_data_locked, sizeof(read_data_locked), cmd);
if (ret == BOOTROM_ERROR_NOT_PERMITTED) {
printf("Locked read failed as expected\n");
} else {
printf("ERROR: ");
if (ret) {
printf("Locked read failed with error %d\n", ret);
} else {
printf("Locked read succeeded. Data read is \"%s\"\n", read_data_locked);
}
}
return 0;
}
This firmware image was imported from the pico-examples repository.
Copyright 2020 (c) 2020 Raspberry Pi (Trading) Ltd.
Redistribution and use in source and binary forms, with or without modification, are permitted provided that the
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