mcp2221_flash.h File Reference

Low-level access to MCP2221 persistent flash sections. More...

#include <stddef.h>
#include <stdint.h>
#include "mcp2221.h"

Include dependency graph for mcp2221_flash.h:

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Functions
mcp2221_error_code_t	mcp2221_flash_read (mcp2221_t *dev, uint8_t section, uint8_t out[60])
	Read one MCP2221 flash section. More...
mcp2221_error_code_t	mcp2221_flash_write (mcp2221_t *dev, uint8_t section, const uint8_t data[60])
	Write one MCP2221 flash section using the legacy 60-byte payload. More...
mcp2221_error_code_t	mcp2221_flash_write_ex (mcp2221_t *dev, uint8_t section, const uint8_t *data, size_t data_len)
	Write a length-delimited MCP2221 Write Flash Data payload. More...
mcp2221_error_code_t	mcp2221_flash_send_password (mcp2221_t *dev, const uint8_t pwd[8])
	Send the eight-byte flash access password. More...

Detailed Description

Low-level access to MCP2221 persistent flash sections.

Definition in file mcp2221_flash.h.

Function Documentation

mcp2221_flash_read()

mcp2221_error_code_t mcp2221_flash_read	(	mcp2221_t *	dev,
		uint8_t	section,
		uint8_t	out[60]
	)

Read one MCP2221 flash section.

The raw 60-byte payload returned by the selected section is copied to out without further interpretation.

Public section identifiers include:

• MCP2221_FLASH_DATA_CHIP_SETTINGS
• MCP2221_FLASH_DATA_GP_SETTINGS
• MCP2221_FLASH_DATA_USB_MANUFACTURER
• MCP2221_FLASH_DATA_USB_PRODUCT
• MCP2221_FLASH_DATA_USB_SERIALNUM
• MCP2221_FLASH_DATA_CHIP_SERIALNUM

Parameters

[in]	dev	Open MCP2221 device handle.
[in]	section	Flash section identifier. Must be one of the public flash section identifiers.
[out]	out	Buffer receiving exactly 60 section-data bytes.

Returns

MCP2221_ERR_OK on success, MCP2221_ERR_FLASH_READ when the device rejects the flash-read command, MCP2221_ERR_INVALID for invalid arguments, or another mcp2221_error_code_t value on failure.

mcp2221_flash_send_password()

mcp2221_error_code_t mcp2221_flash_send_password	(	mcp2221_t *	dev,
		const uint8_t	pwd[8]
	)

Send the eight-byte flash access password.

This command supplies the password used by subsequent flash-write commands on password-protected devices. The MCP2221 does not validate pwd when this command is accepted; the password is checked only when a flash write is attempted. MCP2221_ERR_OK therefore means that the password command was accepted, not that pwd was correct.

Parameters

[in]	dev	Open MCP2221 device handle.
[in]	pwd	Eight-byte flash access password.

Returns

MCP2221_ERR_OK when the password command is accepted, MCP2221_ERR_FLASH_PASSWD when the device refuses the password command (for example after the failed-write password limit has been reached), MCP2221_ERR_INVALID for invalid arguments, or another mcp2221_error_code_t value on failure.

Warning

Three flash writes attempted with an incorrect supplied password exhaust the device's password-attempt limit. The MCP2221 then refuses further passwords until the device is reset. Do not retry password-protected flash writes blindly after a write fails.

mcp2221_flash_write()

mcp2221_error_code_t mcp2221_flash_write	(	mcp2221_t *	dev,
		uint8_t	section,
		const uint8_t	data[60]
	)

Write one MCP2221 flash section using the legacy 60-byte payload.

The 60 bytes are copied to Write Flash Data report bytes 2 through 61. This is sufficient for chip settings, GP settings, and USB string descriptors of up to 29 UTF-16 code units. Use mcp2221_flash_write_ex() when the complete 62-byte write payload is required.

Parameters

[in]	dev	Open MCP2221 device handle.
[in]	section	Writable flash section identifier. Valid values are MCP2221_FLASH_DATA_CHIP_SETTINGS through MCP2221_FLASH_DATA_USB_SERIALNUM. MCP2221_FLASH_DATA_CHIP_SERIALNUM is read-only.
[in]	data	Exactly 60 Write Flash Data payload bytes, corresponding to report bytes 2 through 61.

Returns

MCP2221_ERR_OK on success, MCP2221_ERR_FLASH_WRITE when the device rejects the flash-write command, MCP2221_ERR_INVALID for invalid arguments, or another mcp2221_error_code_t value on failure.

Warning

This is a low-level persistent write. The caller is responsible for supplying a valid payload for the selected section.

See also

mcp2221_flash_write_ex()

mcp2221_flash_write_ex()

mcp2221_error_code_t mcp2221_flash_write_ex	(	mcp2221_t *	dev,
		uint8_t	section,
		const uint8_t *	data,
		size_t	data_len
	)

Write a length-delimited MCP2221 Write Flash Data payload.

Bytes from data are copied starting at report byte 2, after the command and flash-section bytes. Up to 62 bytes can therefore be supplied. This permits a maximum-length MCP2221 USB string descriptor: its two descriptor metadata bytes followed by 60 UTF-16LE data bytes.

For USB manufacturer, product, and serial-number sections, data starts with the USB descriptor length and descriptor type (0x03), followed by the UTF-16LE string data. The caller remains responsible for constructing a section-valid payload.

Parameters

[in]	dev	Open MCP2221 device handle.
[in]	section	Writable flash section identifier. Valid values are MCP2221_FLASH_DATA_CHIP_SETTINGS through MCP2221_FLASH_DATA_USB_SERIALNUM. MCP2221_FLASH_DATA_CHIP_SERIALNUM is read-only.
[in]	data	Write Flash Data payload copied to report byte 2 onward.
[in]	data_len	Number of bytes in data. Must be from 1 through 62.

Returns

MCP2221_ERR_OK on success, MCP2221_ERR_FLASH_WRITE when the device rejects the flash-write command, MCP2221_ERR_INVALID for an invalid section, pointer, or payload length, or another mcp2221_error_code_t value on failure.

Warning

This is a low-level persistent write. The caller is responsible for supplying a valid payload for the selected section.