Problem using synchronous transfer

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From: Mark Plessers
Date: Tue, 10 Feb 1998 00:00

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Hello,

We're making a camera with a SCSI-interface. The �-processor
(which takes care of the communication) is connected
with an AM53CF94 SCSI-controller. The SCSI-card in my PC is an
Adaptec AHA-2940U (camera is externaly connected, single ended).
I'm now trying to speed things up by using synchronous
communications.
After some problems, I could negotiate the speed with the
SCSI-card, and can use an 'offset' of 0x0F and a 'transfer
period factor' of 0x19 (100ns). After converting this factor
to 0x04 and storing this values in the registers of the
controller (which has a clock of 40 MHz), things doesn't
work correctly. The problem is that the communication
(in blocks of 4kB) isn't at 10MHz, but approx. 2.7MHz
(which is slower then asynchronous transfer).

Remark : SCSI-bus is is 8bit, the DMA-transfer to the
         controller is 16bit.

Does somebody know what could be wrong? All suggestions
(or information) are welcome.

Greeting,
Mark
--
Mark Plessers [mark.plessers@innet.be]

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From: "Mark Plessers" <mark.plessers@club.innet.be>
Subject: Problem using synchronous transfer
Date: 1998/02/10
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