Do you hold the metal pads with your thumbs and index fingers tightly on top and bottom of metal pads? ==> yes
Maybe the readings get distorted by something else - by source of power or USB or some noisy piece of electronics nearby? ==> not used usb poower.
Maybe the power supply is shaky as described on MOD-EKG's product page in the FAQ at the bottom? ==> yes. i use coin battery for TEST1. ==> after reading in the FAQ, i use JTAG(MSP430-JTAG-ISO-MK2) external power for TEST2 ==> Test1 and Teset2 is all same not EKG waveform.
How can i get right EKG waveform?
I have another question. When i tested as follow. - use Coin batter at the back of MOD-EKG. - disconnect exteranl serial port. - disconnect jtag connector.
after then, i contact my thumb and finger. In the LCD Arrow blink and realtime change hearrate. My hearrate is 71.
But, after i connect serial port(to coverter USB), I conntact my thumb and finger, arrow not blinkg and not change heratrate number realtime. When use External power in Jtag(MSP430-JTAG-ISO-MK2), all same thing.
Why not blinking in exteranl connect serial or jtag ??
Last post by LubOlimex - July 25, 2022, 10:58:00 am
Hmm, it actually shows that it reads alright (scale is proper, there is different data coming in, it is not missing or a straight line or something), but the overall reading is not what you would expect from EKG.... Do you hold the metal pads with your thumbs and index fingers tightly on top and bottom of metal pads? Maybe the readings get distorted by something else - by source of power or USB or some noisy piece of electronics nearby? Maybe the power supply is shaky as described on MOD-EKG's product page in the FAQ at the bottom?
Last post by LubOlimex - July 21, 2022, 02:28:01 pm
There are no differences in the pinout between EXT and IND version. Basically in the IND version the main chip is different so that it allows lower temperature operation (down to -45C) at the cost of maximum frequency (IND chip can work up to 650MHz, while EXT chip can work up to 800MHz).
Umm header 4 can be investigated from the board schematic. Signals from it go to the main chip, some go the AXP209 and two of all signals go to the LCD connector, as can be seen here:
Notice that Olimex STM32-E407 is open-hardware board, you can get the Eagle sources and measure yourself.
It is relatively easy to take every 2D measure you want with the older versions of the Eagle software. You can open the board file (.brd) with Eagle (the freeware version/license is enough) and take any measure with the "Draw a dimension" tool. The measurements should be done in the .brd file of the board design - a good idea would be to disable some of the layers for better visibility of the measurement (from Layer settings... -> Display and click to enable/disable layers).
Personally I use EAGLE 7.5.0 Light (free version) to measure.