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Add pico_get_unique_board_id_string API #281

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merged 3 commits into from
Mar 30, 2021
Merged

Add pico_get_unique_board_id_string API #281

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7af853d
Add pico_get_unique_board_id_string API
earlephilhower Mar 25, 2021
c40000b
Clean up -Wconversion=error issues
earlephilhower Mar 25, 2021
e18a4f1
Address review comments, fix api typing
earlephilhower Mar 27, 2021
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3 changes: 2 additions & 1 deletion src/rp2_common/pico_stdio_usb/CMakeLists.txt
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Original file line number Diff line number Diff line change
Expand Up @@ -13,9 +13,10 @@ if (TARGET tinyusb_device_unmarked)
tinyusb_device_unmarked
pico_stdio
pico_time
pico_unique_id
)

target_compile_definitions(pico_stdio_usb INTERFACE
PICO_STDIO_USB=1
)
endif()
endif()
11 changes: 9 additions & 2 deletions src/rp2_common/pico_stdio_usb/stdio_usb_descriptors.c
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Expand Up @@ -30,6 +30,7 @@

#include "tusb.h"
#include "pico/stdio_usb/reset_interface.h"
#include "pico/unique_id.h"

#define USBD_VID (0x2E8A) // Raspberry Pi
#define USBD_PID (0x000a) // Raspberry Pi Pico SDK CDC
Expand Down Expand Up @@ -98,10 +99,12 @@ static const uint8_t usbd_desc_cfg[USBD_DESC_LEN] = {
#endif
};

static char usbd_serial_str[PICO_UNIQUE_BOARD_ID_SIZE_BYTES * 2 + 1];

static const char *const usbd_desc_str[] = {
[USBD_STR_MANUF] = "Raspberry Pi",
[USBD_STR_PRODUCT] = "Pico",
[USBD_STR_SERIAL] = "000000000000", // TODO
[USBD_STR_SERIAL] = usbd_serial_str,
[USBD_STR_CDC] = "Board CDC",
#if PICO_STDIO_USB_ENABLE_RESET_VIA_VENDOR_INTERFACE
[USBD_STR_RPI_RESET] = "Reset",
Expand All @@ -121,6 +124,10 @@ const uint16_t *tud_descriptor_string_cb(uint8_t index, uint16_t langid) {
#define DESC_STR_MAX (20)
static uint16_t desc_str[DESC_STR_MAX];

// Assign the SN using the unique flash id
if (!usbd_serial_str[0])
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pico_get_unique_board_id_string(usbd_serial_str, sizeof(usbd_serial_str));

uint8_t len;
if (index == 0) {
desc_str[1] = 0x0409; // supported language is English
Expand All @@ -141,4 +148,4 @@ const uint16_t *tud_descriptor_string_cb(uint8_t index, uint16_t langid) {
return desc_str;
}

#endif
#endif
15 changes: 15 additions & 0 deletions src/rp2_common/pico_unique_id/include/pico/unique_id.h
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Expand Up @@ -57,6 +57,21 @@ typedef struct {
*/
void pico_get_unique_board_id(pico_unique_board_id_t *id_out);

/*! \brief Get unique ID in string format
* \ingroup pico_unique_id
*
* Get the unique 64-bit device identifier which was retrieved from the
* external NOR flash device at boot, formatted as an ASCII hex string.
* Will always 0-terminate.
*
* On PICO_NO_FLASH builds the unique identifier is set to all 0xEE.
*
* \param id_out a pointer to a char buffer of size len, to which the identifier will be written
* \param len the size of id_out. For full serial, len >= 2 * PICO_UNIQUE_BOARD_ID_SIZE_BYTES + 1
*/
void pico_get_unique_board_id_string(char *id_out, size_t len);


#ifdef __cplusplus
}
#endif
Expand Down
13 changes: 13 additions & 0 deletions src/rp2_common/pico_unique_id/unique_id.c
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Expand Up @@ -26,3 +26,16 @@ static void __attribute__((constructor)) _retrieve_unique_id_on_boot(void) {
void pico_get_unique_board_id(pico_unique_board_id_t *id_out) {
*id_out = retrieved_id;
}

void pico_get_unique_board_id_string(char *id_out, size_t len) {
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also for better or worse we've tended to use uint rather than size_t for sizes in APIs

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All done. To preserve hex ordering, we actually need to shift (4 - 4 * (i&1)) or the hex nibbles end up backwards.

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It's a good thing that * has a higher precedence than - 😉

pico_unique_board_id_t temp = retrieved_id;
size_t i;
// Generate hex one nibble at a time
for (i = 0; (i < len - 1) && (i < PICO_UNIQUE_BOARD_ID_SIZE_BYTES * 2); i++) {
size_t bi = i / 2;
int nibble = (temp.id[bi] >> 4) & 0x0F;
temp.id[bi] = (uint8_t)(temp.id[bi] << 4);
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Apologies if this is a stupid question (I'm not a low-level C programmer), but is this modifying the bytes in the underlying retrieved_id ?

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No, this works on the bytes intemp which are copied in line 31.

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this does feel a bit weird though, i'd be tempted to just do

nibble = (temp.id[i/2] >> (4 * (i&1))) & 0xf;

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(I guess @kilograham 's suggestion doesn't modify temp, in which case perhaps there's no need for the copy and you can just access retrieved_id?)

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That's a much better way and it doesn't need the copy, thanks.

id_out[i] = (char)(nibble < 10 ? nibble + '0' : nibble + 'A' - 10);
}
id_out[i] = 0;
}