Sujet : Re: Article on the 8088 bus cycle
De : david.schultz (at) *nospam* earthlink.net (David Schultz)
Groupes : comp.archDate : 17. May 2024, 01:05:03
Autres entêtes
Message-ID : <N2ydnXTdt7uCDNv7nZ2dnZfqnPSdnZ2d@earthlink.com>
References : 1 2 3 4 5 6 7
User-Agent : Mozilla Thunderbird
On 5/16/24 4:21 PM, BGB-Alt wrote:
Seems I was wrong about something before:
The combination of CMD0+CS is what selects SPI mode (for normal SD mode, the CS signal would not be asserted).
I was mistaken in thinking that it was the stream of FF bytes and then asserting CS near the end (say, the init procedure for the SDcard involving sending a large number of FF bytes at a fairly low speed, then sending some other commands and boosting the speed to the intended operating speed).
The low speed was a holdover from its previous life as the MMC card standard. (I still have a 64MB MMC card.) Which were intended to be a multi-drop solution. As such some of the signal lines were open-drain/collector so the speed was limited by the pullup resistor and parasitic capacitance.
-- http://davesrocketworks.comDavid Schultz
Article on the 8088 bus cycle
Re: Article on the 8088 bus cycle
