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Forum: ARM programming with GCC/GNU tools Code to enable SPI mode in old jlink V8 AT91sam7s


von Djalma F. (Company: School) (dbfonseca)


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Hello Friends, I'm new to microcontrollers, but I have one question.

Is it possible to write new code (SAM-BA) in this old device to enable 
SPI module to read this card?

If possible can someone help me?

New SD card generation is Low Voltage 1.8v and I'm trying to program a 
reader, this Jlink has two Low-level converts from 3.3 to 1.8v. That's 
why I'm trying to use it.

The pic is just to show the ideia!

Ps: I don't understand programming (make code) But learned to use 
SAM-BA.

Thanks in advantage

von Jim M. (turboj)


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Djalma F. wrote:
> New SD card generation is Low Voltage 1.8v

Nope. Voltage for SPI mode (and 25 MHz SD modes) is still 3.3 Volts.

And I would not trust your setup to run more than the default 25 MHz - 
maybe even less. Flying cables are bad for signal (and power) integrity.

LibJaylink - as used in OpenOCD - can send raw JTAG sequences IIRC. This 
could in theory be (ab)used in order to implement SPI communication with 
the SD card, eliminating the need to re-program the JLInk device 
altogether.

One problem: I don't know whether the JTAG timing matches SD's SPI 
timing requirements. Try running low speed first.

Also note that SD cards come up in open drain mode and need a pullup 
resistor on the MISO line.

von Djalma Fonseca (Guest)


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Thanks for answer!

Well, you're right about 3.3v and 25Mhz in SDcards.
This Jlink is out of use but still working. My desire is to change the 
internal software to read and write SD card using SPI inside module.

This Box has two ALVC164245 (low Shifting Transceiver) Later I can use 
it to implement 1.8V or 3.3V (even for eMMC module reader).

I'd like to run this in Linux.

If this Jlink isn't supporting for this, can you help fine other 
"developer board that works for this purpose? I need this output as pic 
bellow.


Thanks
Djalma, Brazil +55 19982290220

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