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apache37
Joined: 04 Jun 2004
Posts: 76
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 Posted: Sat Apr 23, 2005 6:46 am Post subject: Max speed for ee-sio |
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I was wondering what was the max speed of the sio on the ps2 side? I can connect at 115k no problem but it would be nice to get a special 1.54mbps serial card and hook up to the ps2 at a much higher speed for a more robust GDB setup. My concern is replacing the current MAX chip with a faster one (the external box) and seeing what the ps2 sio speed limit really is.
Any ideas?? |
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pixel
Joined: 30 Jan 2004
Posts: 791
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| Posted: Sat Apr 23, 2005 8:12 am Post subject: |
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| Code: | | brd = CPUCLK / (baudrate * 256); |
With CPUCLK beeing 294912000 and the following constraint: | Code: | while ((brd >= 256) && (++bclk < 4))
brd /= 4; |
The exercise to find the possible values of baudrate is left to the reader.
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pixel: A mischievous magical spirit associated with screen displays. The computer industry has frequently borrowed from mythology. Witness the sprites in computer graphics, the demons in artificial intelligence and the trolls in the marketing department. |
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apache37
Joined: 04 Jun 2004
Posts: 76
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| Posted: Sat Apr 23, 2005 8:34 am Post subject: |
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Does this say anything about the actual speed limit on the ps2?
I just figured there was a max based a the chip not certain if its just based on the EE. |
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pixel
Joined: 30 Jan 2004
Posts: 791
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| Posted: Sat Apr 23, 2005 10:26 am Post subject: |
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This was extracted from the code which is used to init the sio port.
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pixel: A mischievous magical spirit associated with screen displays. The computer industry has frequently borrowed from mythology. Witness the sprites in computer graphics, the demons in artificial intelligence and the trolls in the marketing department. |
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apache37
Joined: 04 Jun 2004
Posts: 76
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| Posted: Sat Apr 23, 2005 12:07 pm Post subject: |
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| ah. is this part of the kernel then? |
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pixel
Joined: 30 Jan 2004
Posts: 791
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| Posted: Sat Apr 23, 2005 7:18 pm Post subject: |
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Correct.
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pixel: A mischievous magical spirit associated with screen displays. The computer industry has frequently borrowed from mythology. Witness the sprites in computer graphics, the demons in artificial intelligence and the trolls in the marketing department. |
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TerryMathews
Joined: 31 Mar 2005
Posts: 19
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| Posted: Thu Jun 23, 2005 2:38 am Post subject: |
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Either baudrate is not in bps, or brd allows values less than 256.
256=cpu/(baudrate*256) gives an answer of 4500.
I also noticed that baudrate * 256 yields 115200... :) |
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hno
Joined: 10 Apr 2004
Posts: 7
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| Posted: Sat Aug 27, 2005 9:00 am Post subject: |
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| If my math is correct speeds up to 1.152Mbps should be supported (brd = 1, bclk = 0). Maybe the double if brd = 0 is supported (probably not). |
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hno
Joined: 10 Apr 2004
Posts: 7
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| Posted: Sat Aug 27, 2005 10:50 am Post subject: |
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From looking more closely at the specifications and source I find the following
| Code: | IMBUSCLK = CPUCLK(294912000) / 8 = 36.864MHz
SCLK = UNKNOWN
SIO_LCR line control register
SCS(bit 6:5) clock select (baud rate)
00 -> IMBUSCLK
01 -> IMBUSCLK / baud rate generator
10 -> SCLK
11 -> SCLK / baud rate generator
SIO_BGR baud rate generator
BCLK(bit 9:8) clock select
00 -> 2
01 -> 8
10 -> 32
11 -> 128
BRD(bit 0:7) divisor
baud rate generator = BCLK * BRD * 16
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So the max rate the chip will output it's SIO signals is IMBUSCLK (36.864Mbps), with the next available rate being IMBUSCLK / 32 (2 * 1 * 16) = 1.152Mbps. No idea what the electict characteristics of the signals looks like at these speeds however.
For most normal baud rates there is several possible combinations of BCLK and BRD. But don't trust the precomputed tables in Toshiba documentation.. (80 / 4 is not 40). |
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apache37
Joined: 04 Jun 2004
Posts: 76
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| Posted: Fri Sep 02, 2005 5:16 am Post subject: |
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| This is interesting. Anyone know of where to purchase a high-speed serial card for pc? I mean beyond 230k and more like 1mbit. |
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