Turn on suggestions
Auto-suggest helps you quickly narrow down your search results by suggesting possible matches as you type.
Showing results for
Topic Options
- Subscribe to RSS Feed
- Mark Topic as New
- Mark Topic as Read
- Float this Topic for Current User
- Bookmark
- Subscribe
- Mute
- Printer Friendly Page
Accessing the Control/FIFO registers of NI 8422 in DOS
naru
Member
05-18-2005 09:08 AM
Options
- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Report to a Moderator
Using the drivers niboot.exe and ni-pnp.exe driver files we are able to access the COM 1-4 ports on the card as these files create mapping of the COM ports and provides the equivalent base address however the base address of the Control Register, Transmitter/Reciever FIFO register are not specified which is necessary to monitor in order to transmitt/recieve data using the DOS and the code in C.
The solution to look for is either look for the memory/base address of the 8422 card or the function in C language which can access the Control Register, Transmitter/Reciever FIFO register of the card.
Also attacthed an document file for reference.
Thanks
bye
naru
The solution to look for is either look for the memory/base address of the 8422 card or the function in C language which can access the Control Register, Transmitter/Reciever FIFO register of the card.
Also attacthed an document file for reference.
Thanks
bye
naru
Rodney_Greenstr
NI Employee (retired)
05-19-2005 02:25 PM
Options
- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Report to a Moderator
Naru,
The BIOS RAM data area contains the I/O base address of each COM port, up to 4 ports. The BIOS RAM data area is located at memory address 40:0000 (Segment 40, Offset 0). For example, on my machine, the first 8 bytes starting from address 40:0000 are: F8 03 F8 02 E8 03 E8 02. So, starting with COM1, the base addresses are: 3F8 2F8, 3E8, and 2E8.
The BIOS RAM data area contains the I/O base address of each COM port, up to 4 ports. The BIOS RAM data area is located at memory address 40:0000 (Segment 40, Offset 0). For example, on my machine, the first 8 bytes starting from address 40:0000 are: F8 03 F8 02 E8 03 E8 02. So, starting with COM1, the base addresses are: 3F8 2F8, 3E8, and 2E8.
05-30-2005 08:57 AM
Options
- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Report to a Moderator
Hi Rodney Greenstreet,
Well the solution provided is already in the document file NIserial.doc which was attacthed when the query was posted in the forum.
The solution we are looking for is actually, if it is possible to obtain the base address of the Control/FIFO registers of NI 8422 and NOT the COM port base address.
Or is there any other method of accessing these registers without using the drivers.
Thank you
naru
Well the solution provided is already in the document file NIserial.doc which was attacthed when the query was posted in the forum.
The solution we are looking for is actually, if it is possible to obtain the base address of the Control/FIFO registers of NI 8422 and NOT the COM port base address.
Or is there any other method of accessing these registers without using the drivers.
Thank you
naru
Rodney_Greenstr
NI Employee (retired)
05-31-2005 09:30 AM
Options
- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Report to a Moderator
Naru,
The base address of the COM port is necessary in order to determine the I/O address of the registers on the 16550 based UART. For example, the address of the Line Control Register for COM port 1 is calculated by adding the Base Address of COM port 1 + Offset 3. The following is a table that gives the offset of each register. You can obtain more information by downloading the datasheet of the UART used by the 8422 at www.exar.com (16C654).
Register Offset
RX Buffer 0
TX Buffer 0
Interrupt Enable 2
FIFO Control Register 2
Line Control Register 3
Modem Control Register 4
Line Status Register 5
Modem Status Register 6
Scratch Register 7
The base address of the COM port is necessary in order to determine the I/O address of the registers on the 16550 based UART. For example, the address of the Line Control Register for COM port 1 is calculated by adding the Base Address of COM port 1 + Offset 3. The following is a table that gives the offset of each register. You can obtain more information by downloading the datasheet of the UART used by the 8422 at www.exar.com (16C654).
Register Offset
RX Buffer 0
TX Buffer 0
Interrupt Enable 2
FIFO Control Register 2
Line Control Register 3
Modem Control Register 4
Line Status Register 5
Modem Status Register 6
Scratch Register 7
