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Discussion Groups

Discussion Groups | Freescale DSPs | MISO

Technical discussions about Freescale (Motorola) DSPs (including the DSP56000, DSP56300, DSP56600, 56800 DSPs).

  

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MISO - Jacob Christ - Mar 23 22:33:00 2004



Does anyone know if the MISO line on the DSP56F8xx chip has the pull up turned on in master mode?
 
Jacob


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RE: MISO - Litinas, Terry - Mar 24 12:28:00 2004

Jacob,
 
I don't know if  the data sheet or users manual actually says but we use a 56F807 in spi master mode and have 4.7K pull ups to 3.3V on both MISO and MOSI and it seems to work fine.
 
Terry Litinas
-----Original Message-----
From: Jacob Christ [mailto:j...@pontech.com]
Sent: Tuesday, March 23, 2004 5:33 PM
To: 'Motoroladsp'
Subject: [motoroladsp] MISO

Does anyone know if the MISO line on the DSP56F8xx chip has the pull up turned on in master mode?
 
Jacob


_____________________________________
/groups.php3




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RE: MISO - Jacob Christ - Mar 24 19:09:00 2004

Terry / whom ever,
 
Thanks for the info Terry, I will add the pull ups to the next rev, but let me rephrase... 
 
I have a board that does not have an external pull-ups on the MISO bus.  I'm trying to detect if a daughter board that has a CPLD tied to the SPI bus is present.  If the board is not connected I read back all 1's, but I'm curious if this pin (MISO) is pulled up internally or if it's just luck (latched up) that I get all one's.  On the next rev I'll add the pull-ups to guarantee the detection, but it's the 50 boards I already have that I'm trying to figure out if I need to dead bug a pull-up or if I'm good to go.
 
Jacob
 
P.S. Thanks to everyone for so much help on the JTAG programming question.
From: Litinas, Terry [mailto:t...@itwbe.com]
Sent: Wednesday, March 24, 2004 4:28 AM
To: 'Jacob Christ'; 'Motoroladsp'
Subject: RE: [motoroladsp] MISO

Jacob,
 
I don't know if  the data sheet or users manual actually says but we use a 56F807 in spi master mode and have 4.7K pull ups to 3.3V on both MISO and MOSI and it seems to work fine.
 
Terry Litinas
-----Original Message-----
From: Jacob Christ [mailto:j...@pontech.com]
Sent: Tuesday, March 23, 2004 5:33 PM
To: 'Motoroladsp'
Subject: [motoroladsp] MISO

Does anyone know if the MISO line on the DSP56F8xx chip has the pull up turned on in master mode?
 
Jacob


_____________________________________
/groups.php3


_____________________________________
/groups.php3






(You need to be a member of motoroladsp -- send a blank email to motoroladsp-subscribe@yahoogroups.com )

Re: MISO - Douglas Holub - Mar 24 22:45:00 2004

Even if the pull-up is disabled while the SPI is enabled, the pin is a GPIO with the internal pull-up enabled when it comes out of reset. You could detect the presence or absence of the daughter card first, and then enable the SPI.
----- Original Message -----
From: Jacob Christ
To: 'Litinas, Terry' ; 'Motoroladsp'
Sent: Wednesday, March 24, 2004 1:09 PM
Subject: RE: [motoroladsp] MISO

Terry / whom ever,
 
Thanks for the info Terry, I will add the pull ups to the next rev, but let me rephrase... 
 
I have a board that does not have an external pull-ups on the MISO bus.  I'm trying to detect if a daughter board that has a CPLD tied to the SPI bus is present.  If the board is not connected I read back all 1's, but I'm curious if this pin (MISO) is pulled up internally or if it's just luck (latched up) that I get all one's.  On the next rev I'll add the pull-ups to guarantee the detection, but it's the 50 boards I already have that I'm trying to figure out if I need to dead bug a pull-up or if I'm good to go.
 
Jacob
 
P.S. Thanks to everyone for so much help on the JTAG programming question.
From: Litinas, Terry [mailto:t...@itwbe.com]
Sent: Wednesday, March 24, 2004 4:28 AM
To: 'Jacob Christ'; 'Motoroladsp'
Subject: RE: [motoroladsp] MISO

Jacob,
 
I don't know if  the data sheet or users manual actually says but we use a 56F807 in spi master mode and have 4.7K pull ups to 3.3V on both MISO and MOSI and it seems to work fine.
 
Terry Litinas
-----Original Message-----
From: Jacob Christ [mailto:j...@pontech.com]
Sent: Tuesday, March 23, 2004 5:33 PM
To: 'Motoroladsp'
Subject: [motoroladsp] MISO

Does anyone know if the MISO line on the DSP56F8xx chip has the pull up turned on in master mode?
 
Jacob


_____________________________________
/groups.php3


_____________________________________
/groups.php3




_____________________________________
/groups.php3



(You need to be a member of motoroladsp -- send a blank email to motoroladsp-subscribe@yahoogroups.com )