From: Joerg Hansmann (info_at_jhansmann.de)
Date: 2002-03-10 01:47:58
Hi,
----- Original Message -----
From: John Morrison <jmorrison_at_ahc.net.au>
To: buildcheapeeg <buildcheapeeg_at_yahoogroups.com>
Sent: Wednesday, March 06, 2002 5:20 PM
Subject: [buildcheapeeg] Question for Hardware Guys
> Just a (hopefully) Quick Question!
>
> What instructions can you give your hardware device
> eg Set sampling rate
> AND if you know what is the actual data sent over the RS232
> eg MAYBE 02 03 04 :-)
The modularEEG uses essentially the same firmware as the
RS232EEG. At the moment it does not receive any commands.
Sample rate is either 200Hz or 256Hz (depending on a #define
at compile time).
The datastream consists of frames sent with 57600 baud 1 startbit, 1 stopbit,
no parity:
enhanced protocol (version 2):
byte synch_1 // is always $a5
byte synch_2 // is always $5a
byte version // is 0x02 (tells the PC, which protocol is running)
byte frame_counter // is 0x00 at startup. increment 1 for each data frame. wraparound 255->0
byte ch1_high // bit pattern is 000000bb. bb are the 2 high bits of 10 bit AD-value
byte ch1_low
byte ch2_high // bit pattern is 000000bb. bb are the 2 high bits of 10 bit AD-value
byte ch2_low
byte ch3_high // bit pattern is 000000bb. bb are the 2 high bits of 10 bit AD-value
byte ch3_low
byte ch4_high // bit pattern is 000000bb. bb are the 2 high bits of 10 bit AD-value
byte ch4_low
byte ch5_high // bit pattern is 000000bb. bb are the 2 high bits of 10 bit AD-value
byte ch5_low
byte ch6_high // bit pattern is 000000bb. bb are the 2 high bits of 10 bit AD-value
byte ch6_low
byte switches // 1 byte digital inputs (PD2..PD5) in the lower 4 bits.
all together 17 bytes per frame.
Regards,
Joerg
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