gca_pi02-en
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— | gca_pi02-en [2018/12/04 14:54] (current) – created - external edit 127.0.0.1 | ||
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+ | ====== GCA_PI02 | ||
+ | [[english|{{ | ||
+ | [[english|Content]] -> [[hardware-en|Hardware]] -> [[hardware-en# | ||
+ | * [[GCA1-PI01-en|GCA-PI01]] | [[: | ||
+ | * [[mgv-overview-en|The GCA modules]] | ||
+ | * [[: | ||
+ | |||
+ | |||
+ | \\ | ||
+ | ^^^^By Peter Giling ^^^^ | ||
+ | [[http:// | ||
+ | \\ | ||
+ | ===== The real thing ===== | ||
+ | | | ||
+ | | A nice and easy to assemble board is available now.\\ No Surface Mount Devices (SMD) are used. | | ||
+ | |||
+ | ===== Description. ===== | ||
+ | There is not really much to explain about this board.\\ | ||
+ | The two I2C lines, together with ground and +5V are all in the same connection cable.\\ | ||
+ | Two chips MCP23017 are used, each capable of adressing 16 I/O lines, thus 32 in total for 1 board.\\ | ||
+ | 4 Of these boards can be linked together to one GCA_PI01, making 128 I/O lines available on 1 Raspberry PI.\\ | ||
+ | |||
+ | ===== I2C system ===== | ||
+ | |||
+ | I2C is basicly made for communication between chips, together on one board.\\ | ||
+ | Therefore, according to specifications , the total length of all SDA and SCL wires together should not exceed 1 meter (3' 4'' | ||
+ | This system will be made with addional line drivers, making a total length of 10 meters accessable.\\ | ||
+ | Each board is provided with an extra line driver P82B715 and a low drop voltage regulator to have 3.3 V available.\\ | ||
+ | The regulator skips the need of transporting 3.3 V from the Raspi, which could give more problems than profit.\\ | ||
+ | |||
+ | |||
+ | ===== Address selection ===== | ||
+ | ^ Board # ^ dip1 ^ dip2 ^ I/O ports ^ I2C Address ^ | ||
+ | | 1 | OFF | OFF | 1..32 | 0x20-0x21 | ||
+ | | 2 | OFF | ON | 33..64 | ||
+ | | 3 | ON | OFF | 65..96 | ||
+ | | 4 | ON | ON | 97..128 | ||
+ | |||
+ | ===== Hardware ===== | ||
+ | ====Boards/ | ||
+ | * [[: | ||
+ | ====Files==== | ||
+ | | {{: | ||
+ | | {{: | ||
+ | | {{: | ||
+ | ^ N.B. Only complete ordered kits will be supported! ^ | ||
+ | |||
+ | \\ | ||
+ | |||
+ | |||
+ | ===== Cable connection. ===== | ||
+ | There are two possibilities for connection cable between the two boards.\\ | ||
+ | The choice is to use RJ45 connectors and Ethernet cable or RJ12 connectors, with the more flexible 6-wire cables, like known from Xpressnet and LocoNet.\\ | ||
+ | Maximum length of cable between GCA_PI01 and the last GCA_PI02 in the chain, (when line drivers are installed) is 10 meter.\\ | ||
+ | Without line-drivers, | ||
+ | It is expected, nut not prooven yet, that Ethernet cable will handle slightly longer cable.\\ | ||
+ | This is all due to the specifactions of I2C.\\ | ||
+ | |||
+ | ===== Power supply ===== | ||
+ | The GCA-PI02 needs 5Vdc.\\ | ||
+ | This 5V can be extracted from Raspberry Pi, if jumper JP1 on GCA-PI01 is set.\\ | ||
+ | If you prefer separate supply for this board, simply use a 5Volt (minimum 0,5A) USB power adapter.\\ | ||
+ | It connects to USB miniconnector V5.\\ | ||
+ | Also it is possible to supply 5 V from this board to Raspberry Pi, if you set jp1.\\ | ||
+ | In that case, do NOT connect 5V power to Raspberry.\\ | ||
+ | |||
+ | It works like this: | ||
+ | |||
+ | The jumper on each GCA_PI01 and _PI02 board connects the 5Volt lines on board with the power line on the interconnection cable between the boards.\\ | ||
+ | In practice, use one 5V power adapter, and connect it with either one of the GCA_PI02 board USB connector, and \\ | ||
+ | set all jumpers on PI01 and PI02 boards, and the used 5V adaptor will supply all connected units.\\ | ||
+ | If you prefer separate 5V adaptors for each board, leave jumpers away.\\ | ||
+ | |||
+ | |||
+ | ===== Pin configuration of ports ===== | ||
+ | |||
+ | ^ Connector | ||
+ | | Pin# | Port# | Port# | Port# | ||
+ | | 1 | x | x | x | x | + 5V | | ||
+ | | 2 | x | x | x | x | 0V | | ||
+ | | 3 | 1 | 9 | 17 | 25 | | ||
+ | | 4 | 2 | 10 | 18 | 26 | | ||
+ | | 5 | 3 | 11 | 19 | 27 | | ||
+ | | 6 | 4 | 12 | 20 | 28 | | ||
+ | | 7 | 5 | 13 | 21 | 29 | | ||
+ | | 8 | 6 | 14 | 22 | 30 | | ||
+ | | 9 | 7 | 15 | 23 | 31 | | ||
+ | | 10 | 8 | 16 | 24 | 32 | | ||
+ | \\ | ||
+ | All I/O numbers are printed on the board itself.\\ | ||
+ | \\ | ||
+ | ===== Electrical limits ===== | ||
+ | Each port can be either source ( connect to 5 V ) or sink ( connect to 0V) of 25 mAmp.\\ | ||
+ | But the total current for each chip ( = 16 ports) is 125 mAmp. (source) or 150 mAmp. (sink).\\ | ||
+ | It is not allowed to source any power of any kind into the ports !\\ | ||
+ | ====Relay board==== | ||
+ | Due to the limited current per unit from the 5V, only one relay board per I/O expander can be connected: \\ | ||
+ | On **I/O1** __or__ **I/O2** and on **I/O3** __or__ **I/O4**.\\ | ||
+ | |||
+ | |||
+ | \\ | ||
+ | |||
+ | =====RJ12===== | ||
+ | {{ : | ||
+ | ^ Pin ^ Usage ^ | ||
+ | | 1 | VDD(+5V)| | ||
+ | | 2 | SCL(B) | | ||
+ | | 3 | VSS(GND) | | ||
+ | | 4 | SDA (B) | | ||
+ | | 5 | VSS(GND) | | ||
+ | | 6 | VDD(+5V)| |
gca_pi02-en.txt · Last modified: 2018/12/04 14:54 by 127.0.0.1