@Graham I do have a cape with EEPROM at address 0x57 but the EEPROM is wiped with nothing on it so I guess that is why the board doesn't populate that address by default. How can I fix that?
On Tuesday, October 30, 2018 at 11:14:50 PM UTC-4, [email protected] wrote: > > Those addresses at 0x54-0x57 are reserved by the kernel driver. > > Unless you have some capes with those EEPROMS populated, there is nothing > actually there. > > --- Graham > > == > > On Tuesday, October 30, 2018 at 7:01:27 PM UTC-5, MG wrote: >> >> The BeagleBoneBlack comes with an "internal" EEPROM connected to i2c-0 >> line. I can see that clearly when I do i2cdetect: >> >> debian@beaglebone:~$ i2cdetect -y -r 0 >> 0 1 2 3 4 5 6 7 8 9 a b c d e f >> 00: -- -- -- -- -- -- -- -- -- -- -- -- -- >> 10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- >> 20: -- -- -- -- UU -- -- -- -- -- -- -- -- -- -- -- >> 30: -- -- -- -- UU -- -- -- -- -- -- -- -- -- -- -- >> 40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- >> 50: UU -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- >> 60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- >> 70: UU -- -- -- -- -- -- -- >> >> It is showing under address 0x50. When I try to do ahexdump I get the >> following values with no issue: >> >> sudo hexdump -C /sys/class/i2c-dev/i2c-0/device/0-0050/eeprom | head >> -5 >> 00000000 aa 55 33 ee 41 33 33 35 42 4e 4c 54 30 30 30 43 >> |.U3.A335BNLT000C| >> 00000010 31 38 33 37 42 42 42 47 30 36 32 32 ff ff ff ff >> |1837BBBG0622....| >> 00000020 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff >> |................| >> * >> 00001000 aa 55 33 ee 41 33 33 35 42 4e 4c 54 30 30 30 43 >> |.U3.A335BNLT000C| >> >> Now I want to add another EEPROM (with cape) on i2c-2 line which is >> supported according to [BBB SRM]( >> https://cdn-shop.adafruit.com/datasheets/BBB_SRM.pdf) section 8.2. It is >> the CAT24C256 as mentioned in the SRM. The allowable address range for the >> expansion cards is 0x54-0x57. When I do i2cdetect I can see the following: >> >> debian@beaglebone:~$ i2cdetect -r -y 2 >> 0 1 2 3 4 5 6 7 8 9 a b c d e f >> 00: -- -- -- -- -- -- -- -- -- -- -- -- -- >> 10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- >> 20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- >> 30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- >> 40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- >> 50: -- -- -- -- UU UU UU UU -- -- -- -- -- -- -- -- >> 60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- >> 70: -- -- -- -- -- -- -- -- >> >> I can see the addresses 0x54-0x57 showing, but when I try hex dump I get >> an error: >> >> hexdump: /sys/class/i2c-dev/i2c-2/device/2-0054/eeprom: Connection >> timed out >> >> Questions: >> >> 1. Why are they showing as U's not actual address numbers? I know U >> stands for used resource? >> 2. Why am I failing to read from that EEPROM? I have tried all addreses >> from 0x54-0x57 with no luck. I can confirm that those addresses are showing >> in /sys/class/i2c-dev/i2c-2/device and the each dir has the following in it: >> >> debian@beaglebone:~$ ls /sys/class/i2c-dev/i2c-2/device/2-0054/ >> -la >> total 0 >> drwxr-xr-x 4 root root 0 Oct 26 19:46 . >> drwxr-xr-x 8 root root 0 Oct 26 19:46 .. >> drwxr-xr-x 3 root root 0 Oct 26 19:47 2-00540 >> lrwxrwxrwx 1 root root 0 Oct 26 19:47 driver -> >> ../../../../../../bus/i2c/drivers/at24 >> -rw------- 1 root root 32768 Oct 26 19:47 eeprom >> -r--r--r-- 1 root root 4096 Oct 26 19:47 modalias >> -r--r--r-- 1 root root 4096 Oct 26 19:47 name >> lrwxrwxrwx 1 root root 0 Oct 26 19:47 of_node -> >> ../../../../../../firmware/devicetree/base/ocp/i2c@4819c000/cape_eeprom0@54 >> drwxr-xr-x 2 root root 0 Oct 26 19:47 power >> lrwxrwxrwx 1 root root 0 Oct 26 19:47 subsystem -> >> ../../../../../../bus/i2c >> -rw-r--r-- 1 root root 4096 Oct 26 19:47 uevent >> >> I can see the addresses mapping into the kernel but when I try to hexdump >> eeprom it doesn't work at all. I though this was supposed to be setup by >> kernel since it is mentioned in BeagleBone SRM. Am I going to need an >> overlay to add to uboot for this? It doesn't make sense since i2c-2 is >> already set up by default i.e. when I connect another device at address >> aside from 0x54-0x57 it shows up fine and I'm able to interface to it? >> >> All I'm trying to do is read from the EEPROM like I did with the >> "internal" one to confirm it is working. What am I doing wrong? >> > -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/beagleboard/5152cbd8-5ca5-499c-b93f-d57ee2a85c79%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
