[asterisk-bugs] [DAHDI-linux 0015261]: [patch] SPI clock timing to SI3210/15 is not as per datasheet

[Asterisk Bug Tracker]

A NOTE has been added to this issue. 
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https://issues.asterisk.org/view.php?id=15261 
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Reported By:                alecdavis
Assigned To:                sruffell
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Project:                    DAHDI-linux
Issue ID:                   15261
Category:                   wctdm
Reproducibility:            always
Severity:                   tweak
Priority:                   normal
Status:                     acknowledged
Target Version:             2.2.0
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Date Submitted:             2009-06-03 04:39 CDT
Last Modified:              2009-06-04 10:19 CDT
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Summary:                    [patch] SPI clock timing to SI3210/15 is not as per
datasheet
Description: 
Referring to Silicon Labs Si3215 datasheet "Figure 7, SPI Timing Diagram",
and capturing SCS, SLCK, SDO, and SDI on a scope revealed some
discrepencies between data sheet and code.

The is true also of Zaptel Code.

The areas of concern are:
  1. Idle state of clock is shown in data sheet as logic 1, Both the
write_8bits and read_8bits have code to SCLK to 1 before CS goes low.
read_8bits has code to set SCLK to logic 0 after CS has gone high.

  2. In read_8bits the reading of SD0 should happen after rising edge of
clock.
Currently it's read immediatley after SCLK is driven low.

If the SCLK idle state of 0 was for safety reasons, what about SDO, it can
be either 0 or 1. I don't think this was the reason.

Would these fix the code in wctdm_voicedaa_check_hook
/* Try to track issues that plague slot one FXO's */

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 (0105986) sruffell (administrator) - 2009-06-04 10:19
 https://issues.asterisk.org/view.php?id=15261#c105986 
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alecdavis:  Hmmm..I made a mistake to flag it for 2.2.0.  But my strong
preference is to let 2.2.0 go out without this change, since I haven't seen
any reports of problems this causes and it's been in the code for so long. 
Then it can go in early into trunk after 2.2.0 is released to let early
adopters hammer on it until it's time for the next release. 

Issue History 
Date Modified    Username       Field                    Change               
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2009-06-04 10:19 sruffell       Note Added: 0105986                          
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