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Pin 8 (UART_DCD) is active low. It is normally 3.3v. When a connection is live this pin is low. This means that when this pin is converted to RS232 voltage levels it will have the correct voltage level for assertion.
Pin 10 (UART_DSR) is an input, with active low logic. It should be connected to the DTR output of the host. When the BISM2 Module is in high speed mode (See definition for S Register 507), this pin should be asserted by the host to ensure that the connection is maintained. A deassertion is taken to mean that the connection should be dropped, or an online command mode is being requested.
Pin 27 (VCC_3V3 monitor) may only be used for monitoring purposes. It must not be used as a current source.
The GPIO pins can be accessed using S Registers 621 to 628. GPIO4 is connected to an LED on the module. If these I/O pins are set for input, then the LED will be driven by the host and appropriate drive current requirements must be satisfied. A Logic 1 switches on the LED.
GPIO3 is also used for DTR output (active low). See S Register 552 & 553.
Analogue 0 and 1 should not exceed 1.8v and S Registers 701 and 702 are used to access them.
3.3Electrical Specifications
3.3.1Absolute Maximum ratings
Absolute maximum ratings for supply voltage and voltages on digital and analogue pins of the Module are listed below; exceeding these values will cause permanent damage.
Parameter
Peak current of power supply
Voltage at digital pins
Voltage at POWER pin
Min
0
3.6
Max
100
3.7
7
Unit
mA
V
V
3.3.2Recommended Operating Parameters
3.3.2.1Power Supply
Signal Name | Pin No | I/O | Voltage level | Comments |
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Vcc | 29 | I | 3.6V to 7.0V | Ityp = 30mA |
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GND | 11, 15, 18, |
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| 6 Ground terminals to be attached |
| 30, 36, 38 |
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| in parallel |
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VCC_3V3 | 27 | O | 3.3V typical | For monitoring only. No current |
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| source |
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3.3.2.2RS-232 Interface
Signal Name | Pin No | I/O | Signal level | Comments |
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UART_TX | 21 | O | VOLmax=0.2V |
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| VOHmin=2.8V |
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UART_RX | 25 | I | VILmax=0.8V |
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| VIHmin=2.1V |
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| VIHmax=3.7V |
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UART_CTS | 19 | I | VILmax=0.8V |
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| VIHmin=2.1V |
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| VIHmax=3.7V |
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