diff --git a/doc/source/index.rst b/doc/source/index.rst index 82d6df97cb5d178fe1d4e6e15bae20a728a6fef2..d63cfa67e35471f3a6bff330c1e6a121f86acaaf 100644 --- a/doc/source/index.rst +++ b/doc/source/index.rst @@ -39,7 +39,6 @@ Contents: source_rst/troubleshooting source_rst/developments source_rst/gallery - source_rst/developing_hardware_components source_rst/archived_version diff --git a/doc/source/source_rst/hardware/mux_2024.rst b/doc/source/source_rst/hardware/mux_2024.rst index 3b4cc2e965d658fa2960ad535556f1d41aea92a2..51d17c06e1a817f9153f77d3a1d295f82d10961e 100644 --- a/doc/source/source_rst/hardware/mux_2024.rst +++ b/doc/source/source_rst/hardware/mux_2024.rst @@ -8,14 +8,20 @@ MUX board v2024 **************************************************** -**TO BE UPDATED** - -The multiplexing of the channels is a mechanical multiplexing based on OMRON's manufacturing relays (G5LE-1-VD 12 VDC). Each relay is combined with -a ZVN4206A power MOFSET. The raspberry has only 30 GPIOs, which is not enough to activate all the 64 electrodes, which represent 512 GPIOs. -We used gpio expander I2C (MCP23017). We have associated these components with an I2C multiplexer of type type TCA9548A from adafruit. -This combination allows to go up to 512 GPIOs and up to 128 electrodes. Each card has its own digital address between 0X70 and 0X77. -In the following presentation for an OhmPi 64 electrodes, we will use the addresses 0X70 for channel A, 0X71 for channel B, 0X72 for channel M and 0X73 for channel N. -0X73 for the N channel. 4 MUX board will be needed to multiplex an OhmPi 64 electrodes. +The MUX board v2024 uses the same technology than the MUX board v2023, i.e. mechanical multiplexing. However it introduces +a new level of flexibility by addressing multiple roles (A, B, M, N), which allows to build OhmPi system with multiple of 8 electrodes. +Users can physically configure the MUX board to address 2 roles (A, B or M, N) or 4 roles (A, B, M, N). With only 32 relays, +it can address 16 or 8 electrodes, for the 2- and 4-role configuration respectively. +Given the reduced number of relays, the MUX board v2024 is interfaced with only two MCP23017 I/O expanders. +This means that up to 4 MUX boards v2024 (i.e. 32-electrode system) can be directly connected to a measurement board v2024. +A newly introduced I2C extension board (featuring a TCA9548A multiplexer) allows to connect up to 32 MUX board v2024, equating to a 256-electrode system. +In theory, up to 8 I2C extension boards can be connected to the measurement board, which would allow to pilot 2048 electrodes. +For obvious practical reasons, such a configuration couldn't be tested and is likely to be limited by the I2C bus being phisically too long, +which would prevent to reach so many GPIOs. +In an effort to mitigate supply shortages, a last addition concerns the power mosfet associated with the relays, +with the possibility to mount two types of components depending on market availability: either ZVN4206A or STP16NF06L. + +Here, we will present how to assemble and configure a 32-electrode system, based on 4 MUX-board v2024 set up to address 2 roles / 16 electrodes each. **PART A** Assembly of MUX board ====================================================== @@ -155,10 +161,22 @@ Required components **PART B** MUX board address ====================================================== -To build an ohmpi it is necessary to have 4 MUX boards, with 4 different addresses. It is therefore necessary to identify each board, by assigning an address, which will be allocated in the OhmPi code. -We present here the addresses selected by default. +A MUX v2024 comes with 2 I/O expanders (MCP23017) addressing 16 relays each. They can be identified by the Raspberry Pi unit +with their I2C address ranging 0x20 - 0x27. Two jumpers allow to shift the addresses two by two based on the following combination: + ++-------------+-----------------+------------------+ +| addresses | Addr1 position | Addr2 position | ++=============+=================+==================+ +| 0x20 - 0x21 | Up | Up | ++-------------+-----------------+------------------+ +| 0x22 - 0x23 | Down | Up | ++-------------+-----------------+------------------+ +| 0x24 - 0x25 | Up | Down | ++-------------+-----------------+------------------+ +| 0x26 - 0x27 | Down | Down | ++-------------+-----------------+------------------+ + -For the A electrode board, we suggest addressing it with address 0x70: .. table:: :align: center