ATA Protocol

Hi All,

Sir,Currently i am working on a Seagate PATA hard drive(Model No-ST3802110A , 80 GB),implementing ATA protocol on that.I am facing some problems while reading the data register of that hard drive.I am working to Standard ATA-3 PIO data in protocol.

I am facing a problem while executing Identify device command.I am performing the flow as per flow mentioned in ATA datasheet as follows:
1) reading status register and checking for BSY bit. I am getting it low whenever hard disk is not busy. So that is fine
2)Now selecting device by setting dev bit low. I am setting it low because it's status should match with the cable_Select pin. In my hardware cable select is connected to ground. So i am writing A0h in device/head register.
3)Reading the status register and checking for BSY and DRDY bits. I am getting BSY = 0 and DRDY = 1. So it is ok.
4)Writing command ECh in command register.[Identify Device = ECh].
5) Checking for Error bit in status register and BSY bit also. I am getting BSY low and ERR bit low. That means no error has occured till now.
5(a)) i have provided a delay of 81 microseconds,before reading the data register.
6) Now I am checking for DRQ bit. But i am not getting DRQ = 1 as per the flow mentioned in ATA-3 Datasheet.
Even if I ignore DRQ bit, and start reading data register, i always get FF00, which is not as per outputs mentioned in datasheet for Identify device command. I am getting all 256 words as FF00h only.

Even i have tried the CHECK POWER MODE command,but i am getting the default values which are stored in Sector(Count and Number) and Cylinder(Count and Number) registers. I should get 00h or 80h or FFh in sector count register. But I am getting 01h which is the default value of this register. That means I am not getting proper response, also hard drive is not setting error bit in status register. So I am not able to guess where the problem is taking place.

So i am facing this problem for last many days and i am not getting any proper documents on internet to sort out this issue.If any body can support me in sorting out this issue,please support me for this.

Thanks & Regards,
Ravi Chobey

Have you looked at the Linux driver source code? They would seem to be a reliable reference point.
--- rod.

as far as documentation goes try this:
google://d0791r4c-ATA

Thanks to all who has send me the replies and also the question viewers for taking time to read ATA question.I have sorted out the issue and now now i am trying to read the first sector of hard disk.

Regards,
Ravi Chobey