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Boardwalk :: Forum List Luminary Micro Forums Design Stellaris 2006
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wildpossum

Junior Boarder

2006/11/24 19:12

External LM3S101 slaves

Hi.

I intend using several LM3S101 uP in my Design entry.

However, I need to flash the 101's via the Evaluation Board. How do I do this? What type of h/w interface need I have on the 101 side?

Can I also debug the 101's as well (using the Evaluation s/w)?

Thanks.
Grahame

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LMI Dan

Moderator

2006/11/28 11:58

Re:External LM3S101 slaves

All you need is to bring out the LM3S101 JTAG signals to a 20-pin JTAG header. You can use the Stellaris Development board schematics for a reference. The schematics are located at the end of the development board user's manual. I don't think Keil (or our driver) will allow you to daisy-chain the multiple JTAG devices together, so you will need a separate JTAG connection for each.

Yes, you can use the eval board to debug and program any Luminary Micro Stellaris device.

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achoox4

Senior Boarder

2007/01/08 13:09

Minimal 811 ref. circ. to program with eval board?

What all is needed for an 811 (or 101/102) to operate such that it can be programmed via JTAG from the eval board?

(Has anybody here yet successfully moved their code off the eval board? I've seen no mention of it...)

I soldered an 811 to a QFP-to-DIP adapter, plugged it into a breadboard, and connected:

-4 power pins to 3.3V.
-4 ground pins
-LDO through 10uF to gnd
-pullups for reset and Trst
-OSC0 and OSC1 to 3.6...MHz crystal and 18pf to gnd.
-4 JTAG pins to the JTAG cable (and grounded the line that goes back to the eval bd. 811's reset)


I tried to flash in a program and got the usual error window (couldn' program, DLL cancelled...).

Since I couldn't verify the oscillator circui with a scope at the time, I insted connected OSC0 with the buffered 6MHz from the eval board. Same result.
Thinking that perhaps a junk program on the 811 was preventing JTAG access, I tried both options above with reset tied low. Same results.

What I'm I missing?
-Any more pins that need connecting?
-I do not understand the function of LDO. Is there a simple way to disable it?
-Are any of the specified xtal options OK, or is 6MHz required? (I used 3.6....MHz because it's the only one listed that I have sitting around.)
-Is a specific brand of crystal (CL=36?) needed?
-Are all power/ground pairs required to be connected for programming? The fewer to connect, the fewer to screw up...)

Older app notes show 15pF for the xtal circuit. Obsolete? Worth trying?

I noticed that in the debugger configuration, there is a place for target PLL frequency, which defaults to 50 for the 811 and 20 for the 101. Does this matter, in the sense that an unprogrammed device does not know how to run its PLL since it's not been told what xtal is has?

Rather than further endanger my expensive, hard-to-obtain/assemble 811/board combos, I'd like to switch to experimenting with a 101 or 102. Does that make any difference other than picking it in the list of targets?

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magnuslundinse

Gold Boarder

2007/01/08 14:34

Re:Minimal 811 ref. circ. to program with eval boa

Hi

I built a 102 board with the same connections, and 0.1uF decoupling capacitors on all GND,VCC pairs, and it works.

LDO is for converting 3.3V to internal 2.5V, must be active.
I use a 1uF low ESR cap for the LDO pin and the chip would not start without it. Even without a crystal attached you can check the oscillator output of OSC1 if there is a signal that tries to drive the crystal.

xtal capacitor values depends on the crystal, 15-18 pF is common, 3.6MHz should work.

A scope is almost a must when building your own board to check signals and communications.

I think there is a serial bootloader on the chips when delivered but this should not disturb the startup and JTAG connection, you will simply debug the bootloader.

Regards,
Magnus

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achoox4

Senior Boarder

2007/01/09 18:18

Re:Minimal 811 ref. circ. to program with eval boa

I've got the circuit at work with me now and the scope shows a nice clock on OSC1, with more than 1V amplitude around 1.6V center.

Trying to verify the solder joints, I tore the TRST pin off the board, but managed to resolder it despite it trying to fold under the package.

Cap on LDO is 10uF (tantalum, I think). I'm going to replace it with an SMD tantalum part from the fresh parts stocks (just in case my through-holes are just too old).

Does the voltage on the LDO pin indicate whether that's working?

After that, I'm out of ideas save for soldering problems. So I'm finally going to switch to a 101/102 to avoid damaging the 811 setup by poking around too much.

Any ideas fom LMI on how to diag the hardware when the debugger says "nope"?

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LMI Eric

Moderator

2007/01/12 11:52

Re:Minimal 811 ref. circ. to program with eval boa

I noticed that you've mentioned 4 JTAG pins and that you did something with TRSTn. In order to access the debug port, you must have TRSTn pulled up. Out of reset, that pin is in JTAG mode and, due to the weak pull-up errata, can appear to be in the 1-2V range to the MCU. That could cause TRSTn to be inadvertently held low, killing your JTAG connection. It would be a good idea to pull up the other JTAG pins for debug purposes.

If your clock looks good and you're LDO is outputting 2.5V, then I'm guessing the issue is probably in the debug port connections.

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