On 05/27/2009 01:59 PM, Jean Delvare wrote: > On Wed, 27 May 2009 13:08:19 +0200, Hans de Goede wrote: >> >> On 05/27/2009 11:15 AM, Andre Prendel wrote: >>> Hi Hans, >>> >>> looking in the datasheet of the TMP421 sensor chip >>> >>> http://focus.ti.com/docs/prod/folders/print/tmp421.html, >>> >>> I saw the following addresses. >>> >>> TMP421 100 11xx >>> TMP422 100 11xx >>> TMP423A 100 1100 >>> TMP423B 100 1101 >>> >>> But the preliminary driver of your students uses 0x2a. >>> >>> /* Addresses to scan */ >>> static unsigned short normal_i2c[] = { 0x2a, I2C_CLIENT_END }; >>> >>> 0x2a == 010 1010b, right? >>> >> Right. >> >>> Do I misunderstand something? >> No, what my students did in there was wrong, they only put the >> address in there to which the sample I gave them is wired >> >> The addresses to scan should be: >> static unsigned short normal_i2c[] = { 0x1c, 0x1d, 0x1e, 0x1f, >> 0x2a, 0x4c, 0x4d, 0x4e, 0x4f, I2C_CLIENT_END }; >> >> But we better run those past Jean, to see if any of >> those are dangerous to scan by default, Jean ? > > 0x2a and 0x4c-0x4f are very popular addresses for hardware monitoring > chips and can be scanned. 0x1c-0x1f is something new, sensors-detect > doesn't even scan 0x1c-0x1e at the moment, only 0x1f is scanned (for > the Maxim MAX6650/MAX6651.) > > Where do the 0x1c-0x1f and 0x2a addresses come from? From the data sheet, the tmp421 has 2 pins which can be 0, floating or 1 and by that combination it can be made to listen on a number of addresses including 0x1c-0x1f and 0x2a, the sample I was using (I'm mailing it to Andre) has both pins floating resulting in it listening on 0x2a, I can confirm atleast this part of the table from the datasheet checks out. > The possible > addresses listed above by Andre were only 0x4c-0x4f. > > On which systems are these chips found? Currently, none that I know of, I ordered samples for the tmp401/tmp411 (which was for an embedded system) and ordered those for the 421 too while I was at it. > If only on embedded systems and > not on PC, the safe option would be to only scan 0x2a and 0x4c-0x4f. Ok, then lets do that. > On > embedded systems, probing won't be used anyway, so devices can be > instantiated at any address, regardless of what the driver lists. > Ack. Regards, Hans
