On 3/8/24 04:20, Heinrich Schuchardt wrote:
On 3/8/24 03:06, E Shattow wrote:
P.S. Found the longer description at https://github.com/milkv-mars/mars-buildroot-sdk/commit/d381610c92827de01b25... https://github.com/milkv-mars/mars-buildroot-sdk/commit/d381610c92827de01b25843786012351b3f35519 as follows: "if configured as 24c04, its address will occupy 0x51, conflicting with the RTC chip pcf85063 on the IO-Board. Refer to: Documentation/misc-devices/eeprom.rst". What does that even mean, it is for Raspberry Pi Compute IO carrier only?
According to https://ww1.microchip.com/downloads/en/devicedoc/doc0180.pdf the chips differ in how their address lines are used. Either they select a chip or a memory address.
The chip is at reg 0x50. So it could be that if you read the upper memory of atmel,24c04 it would use reg 0x51.
https://datasheets.raspberrypi.com/cm4io/cm4io-datasheet.pdf says the CM4IO board has an RTC at address 0x51.
Together with the commit message this really sounds like the smaller chip size is faked due to incompatibility.
Running i2cdetect on my Mars Milk-V board shows that a device is responding to address 0x51:
$ sudo i2cdetect 5 I will probe file /dev/i2c-5. I will probe address range 0x08-0x77. Continue? [Y/n] y 0 1 2 3 4 5 6 7 8 9 a b c d e f 00: 10: 20: 30: -- -- -- -- -- -- UU -- 40: 50: 50 51 -- -- -- -- -- -- -- -- -- -- -- -- -- -- 60: 70:
As you mentioned to have access to a CM module I would like to know what its serial number looks like to understand what if it can be used to detect if we are running U-Boot on full board or a CM module.
For my Milk-V board I have:
MARS-V11-2340-D008E000-xxxxxxxx
Best regards
Heinrich