[EMAIL PROTECTED] wrote:
[EMAIL PROTECTED]"> Ref: ATAPI-5 std (NCITS 340-2000) paragraph 9.14.4.1 describes host termination data-out - of particular interest is response of device to STOP assert; list items c) and d) imply an inter-relationship between DMARQ negate and DDMARDY- negate.
My questions:
1. Is there really a requirement for such a direct relationship between DMARQ negate and DDMARDY- negate?
2. if so, why?
See below for more detailed reasoning.
Cheers
Keith
________________________
From the standard:
"9.14.4.1 Host terminating an Ultra DMA data-out burst
The following steps shall occur in the order they are listed unless otherwise specified......
:
c) The device shall negate DMARQ within tLI after host asserts STOP......
d) The device shall negate DDMARDY- within tLI after host asserts STOP......"
Because of the covering statement, c) must occur before d), but both are the consequence of the same event (STOP assert).
. So, is this saying that DMARQ negate must always occur BEFORE DDMARDY- negate (for host terminate)?
. What about AFTER?
Implies in practice tLI(DDMARDY) > tLI(DMARQ) to guarantee sequence is met. (If =, skew may cause violation at host).
The timing diagram implies that these are independent processes, with no such interdependency (simply dependent on STOP assert).
--
Keith Clausen, STMicroelectronics,
Mail: 1000 Aztec West, Bristol BS32 4SQ, UK
Email: [EMAIL PROTECTED]
Phone: +44 1454 462457 Fax: +44 1454 617910
-- Keith Clausen, STMicroelectronics, Mail: 1000 Aztec West, Bristol BS32 4SQ, UK Email: [EMAIL PROTECTED] Phone: +44 1454 462457 Fax: +44 1454 617910
