SPI Flash

Flash Chip

Boot loader for the RT1 is written on a Winbond W25Q32VIP. This is a 32MBit (4K Byte) SPI flash chip that operates in Single mode and comes in an 8 pin WSON 6X5-MM package. Its contents are locked in because of the P variation in its name that specifies the OTP (Write Once) feature in the chip. This means the contents can't be replaced. We can however replace the entire chip.

Pinout

Below is the pinout for Single mode operation of the chip.

W25Q32 WSON 6X5-MM

Pin	Name	I/O	Function
1	/CS	I	Chip Select Input
2	DO	O	Data Output
3	/WP	I	Write Protect Input
4	GND		Ground
5	DI	I	Data Input
6	CLK	I	Serial Clock Input
7	/HOLD	I	Hold Input
8	VCC		Power Supply (3.3V)

Naming Convention

Chip Series Naming

Replacing the flash

Before starting it is recommended to dump the contents of the chip as it contains unique configuration aspects for the device. Check the firmware section on how to do this

Replacing the chip is not to be taken lightly. It requires a hot air station to remove as it is a surface mounted package with a big ground pane in the center. Beside this there are multiple components close to the chip that need to stay in place.

Removing the shielding

Begin by the shield covering the SOC, Memory and flash chips. This will come of very easily with little force. Take your time doing this.

Removing the shield

Removing the shield

Once removed we have an overview over the most important components

Overview

Removing the chip

To make the flash chip better accessible, the metal that held the shield in place can be bent back slightly. To help the desoldering the back of the PCB should be pre-heated at a low temp before starting work on the front. This will help with removing the chip and its big ground pane. Then start heating the flash chip itself at a low flow to not disturb the components around it. Make sure to heat it properly as forcing the chip off will break the pads on the PCB.

Highlighted Ground Pane

Accessing the flash chip

Chip Removed