2.4 KiB
Modifications
SPI-Flash Memory
SPI-Flash memory can be replaced with an other type. Because the chip is defect, like #69 & #70 or you have an unmanaged-switch with a small flash size, and want to convert it to a managed-variant to run RTLPlayground software on it. Currently RTLPlayground-firmware expects 8 MBit / 2 MiB.
Size
The SOC (RTL837x network chip) used 24-bit address to access the device. This means that in theory, a memory size up to 2^24 x 8-bit = 16777216 x 8-bit = 128 MBit or 16 MiB could be used, this is untested!
Speed
The SOC (RTL837x network chip) is connected via an SPI-BUS to the flash memory. SPI-BUS frequency is 62.5 MHz.
Look in the datasheet for AC Electrical Characteristics and lookup symbol Fr. Maximum value should be equal or higher than 62.5 MHz.
A device that supports the highest possible clock speed is not a better device, nor is the SOC going to run faster. So pick one which have common frequency between 80 MHz to 133 MHz.
Memory speed is dictated by the SPI-BUS clock frequency which is 62.5 MHz.
SPI Operation
By default, SPI-BUS uses CLK, CS, DI and DO. To increase the data throughput without increasing the bus frequency, a single command can run in DUAL SPI operation. This means that for a specific command DI and DO are both used to transfer the data to/from the device. So it makes the data transfer twice as fast. Although the SOC datasheet doesn’t mention it, our software is making use of this mode.
Package
Most use package are SO8-type may also called SOIC8-type. Which can also have different width. Like 150-mil, 208-mil or 300-mil. Best to measure what you need and confirm the measurement with the device-datasheet.
Specification
- Size: At least
16 MBit / 4 MiB(theoretic max.128 MBit / 32 MiB, but is not tested!) - Speed:
62.5 MHzor better. - Support for
DUAL SPI operation.
Known Working
This list is incomplete.
| Brand | Partnumber |
|---|---|
| GigaDevice | GD25Q32E |
| Winbond | W25Q16JV |
| Winbond | W25Q32FV |
| Winbond | W25Q32JV |
| Winbond | W25Q16JL |
| Fundan | FM25Q16A |
NOTE: Part numbers are incomplete. Part numbers may contain additional information such as package, temperature specifications, and even the number of devices on a reel. So always check the datasheet so that you have the right orderable partnumber.