Forums

MISO

Started by Jacob Christ March 23, 2004
Does anyone know if the MISO line on the DSP56F8xx chip has the pull up turned on in master mode?
 
Jacob



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


_____________________________________
Note: If you do a simple "reply" with your email client, only the author of this message will receive your answer.  You need to do a "reply all" if you want your answer to be distributed to the entire group.

_____________________________________
About this discussion group:

To Join:  m...@yahoogroups.com

To Post:  m...@yahoogroups.com

To Leave: m...@yahoogroups.com

Archives: http://www.yahoogroups.com/group/motoroladsp

More Groups: http://www.dsprelated.com/groups.php3



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


_____________________________________
Note: If you do a simple "reply" with your email client, only the author of this message will receive your answer.  You need to do a "reply all" if you want your answer to be distributed to the entire group.

_____________________________________
About this discussion group:

To Join:  m...@yahoogroups.com

To Post:  m...@yahoogroups.com

To Leave: m...@yahoogroups.com

Archives: http://www.yahoogroups.com/group/motoroladsp

More Groups: http://www.dsprelated.com/groups.php3


_____________________________________
Note: If you do a simple "reply" with your email client, only the author of this message will receive your answer.  You need to do a "reply all" if you want your answer to be distributed to the entire group.

_____________________________________
About this discussion group:

To Join:  m...@yahoogroups.com

To Post:  m...@yahoogroups.com

To Leave: m...@yahoogroups.com

Archives: http://www.yahoogroups.com/group/motoroladsp

More Groups: http://www.dsprelated.com/groups.php3




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


_____________________________________
Note: If you do a simple "reply" with your email client, only the author of this message will receive your answer.  You need to do a "reply all" if you want your answer to be distributed to the entire group.

_____________________________________
About this discussion group:

To Join:  m...@yahoogroups.com

To Post:  m...@yahoogroups.com

To Leave: m...@yahoogroups.com

Archives: http://www.yahoogroups.com/group/motoroladsp

More Groups: http://www.dsprelated.com/groups.php3


_____________________________________
Note: If you do a simple "reply" with your email client, only the author of this message will receive your answer.  You need to do a "reply all" if you want your answer to be distributed to the entire group.

_____________________________________
About this discussion group:

To Join:  m...@yahoogroups.com

To Post:  m...@yahoogroups.com

To Leave: m...@yahoogroups.com

Archives: http://www.yahoogroups.com/group/motoroladsp

More Groups: http://www.dsprelated.com/groups.php3




_____________________________________
Note: If you do a simple "reply" with your email client, only the author of this message will receive your answer.  You need to do a "reply all" if you want your answer to be distributed to the entire group.

_____________________________________
About this discussion group:

To Join:  m...@yahoogroups.com

To Post:  m...@yahoogroups.com

To Leave: m...@yahoogroups.com

Archives: http://www.yahoogroups.com/group/motoroladsp

More Groups: http://www.dsprelated.com/groups.php3