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iriver h1x0 - RTC (real time clock) mod
roolku:
--- Quote from: IpaqMan on December 13, 2006, 05:17:03 PM ---I just read in the data sheet that a diode in series with the VCC backup should NOT be used or improper operation will result.
--- End quote ---
Well spotted.
--- Quote ---The data sheet also stated that the supply voltage MUST be held between 1.3 and 3.7 volts, so I will choose either the resistor or a small lithium button cell.
--- End quote ---
I wonder if this is an error/omission in the data sheet. Looking at a similar chip (DS1340 - an alternative if you don't need the alarm) it states http://www.maxim-ic.com/quick_view2.cfm/qv_pk/3914 :
--- Quote ---VBACKUP
Connection for a Secondary Power Supply. For the 1.8V and 3V devices, VBACKUP must be held between
1.3V and 3.7V for proper operation. Diodes placed in series between the supply and the input pin may
result in improper operation. VBACKUP can be as high as 5.5V on the 3.3V device.
--- End quote ---
Which would make more sense...
IpaqMan:
I tend to agree with you that this may be an omission on some data sheets. Some data sheets specify ranges for different models for Vbatt. But some have only one range 39c/38. Since your Hxxx players are working with the 4.2 volt input, I think that this confirms it.
One would think that if the main circuits can handle VCC up to 5.5 then the backup input should be able to do the same.
roolku:
--- Quote from: IpaqMan on December 13, 2006, 01:56:40 PM ---I just received a couple of the RTC chips and hope to do the mod later this week.
--- End quote ---
Just curious how you are getting on. Did you get a chance to try it?
IpaqMan:
I haven't done it yet.
I am a several steps along the way.
1) Got RTC chip
2) Installed VMMWare Rockbox
3) Downloaded rtc.patch
4) Got successful build with rtc.patch
5) Rounded up very small gauge wires and twelve watt soldering iron
Now I need some alone time to solder.
***EDIT
6) Attached wires and tape to the RTC chip
The soldering turned out to be fairly difficult. I think I need even smaller gauge wire than I am using now. I would prefer a gauge so small that moving the wires would not put any stress on any solder points. The wire I am using now is about the same size as the chip leads and is solid.
roolku:
--- Quote from: IpaqMan on December 18, 2006, 02:00:32 PM ---
The soldering turned out to be fairly difficult. I think I need even smaller gauge wire than I am using now. I would prefer a gauge so small that moving the wires would not put any stress on any solder points. The wire I am using now is about the same size as the chip leads and is solid.
--- End quote ---
Yes, I agree, the leverage of the wire is very stressfull for the little pins. I used stranded wire with maybe 6 very thin strands (ripped from an old mouse cable). But still the wire really needs to be kept in a fixed position without any tension once attached.
I made little 90 degree bends, and placed the wire on the chip (legs up) with the wire tip pointing outwards above the pin. While pressing the wire onto the chip and holding it in position with one hand I use the other to dip the prepared soldering iron onto the wire tip to make the bond.
Good luck
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