USB-I/O Interface Adapter GPIO-24. Programmer's Reference Manual.

Command is an 8-byte array of the following format:

Byte 0: GPIO_SET_ADC_CHANNEL_CFG (0x21)

This byte contains command ID (command type). It should be set to 0x21.

Byte 1: ECHO

This byte is used to associate a response received from GPIO-24 adapter with a specific command. Response will contain exactly the same value in its echo byte.

Byte 2:

Bits 7..4	Bits 3..0
EVENT_CONDITION	CHANNEL

Bits 7..4: EVENT_CONDITION

The bits define the condition when USB-I/O adapter sends GPIO_EV_ADC event. It can take on one of the following values:

• GPIO_ADC_EV_NONE (0x0) – No events are sent for current ADC channel.

• GPIO_ADC_EV_BELOW (0x1) – The event is sent when the input voltage descends below the low threshold value. High threshold value is ignored.

• GPIO_ADC_EV_ABOVE (0x2) – The event is sent when the input voltage rises above high threshold value. Low threshold value is ignored.

• GPIO_ADC_EV_OUTSIDE (0x3) – The event is sent when the input voltage exceeds the limits specified by low and high threshold values.

• GPIO_ADC_EV_INSIDE (0x4) – The event is sent when the input voltage is within the limits specified by low and high threshold values.

• GPIO_ACD_EV_ALWAYS (0x5) – The events are sent periodically with predefined interval. The non-zero repeat interval is specified in Byte 3: REPEAT.

For more detailed information about the event generation see Section 7.4, “ADC Event”.

Bits 3..0: CHANNEL

The number of ADC channel:

• 0 – C.1 pin;

• 1 – C.2 pin;

• 2 – C.5 pin;

• 3 – C.6 pin;

• 4 – B.3 pin.

Byte 3: REPEAT

This byte defines the repeat interval for GPIO_EV_ADC event generation. If this byte is non-zero, GPIO-24 adapter sends events each REPEAT * 10 ms. For more detailed information see Section 7.4, “ADC Event”.

Bytes 4..7: LOW_LSB/LOW_MSB/HI_LSB/HI_MSB

These bytes define low and high threshold values. You can set any value from 0 to 0x3FF as low and high threshold values. 0 corresponds to V_RefLow and 0x3FF corresponds to V_RefHi voltage.

Byte 4: LOW_LSB – least significant byte of low threshold value.

Byte 5: LOW_MSB – most significant byte of low threshold value.

Byte 6: HI_LSB – least significant byte of high threshold value.

Byte 7: HI_MSB – most significant byte of high threshold value.

Response is an 8-byte array of the following format:

Byte 0: GPIO_SET_ADC_CHANNEL_CFG (0x21)

This byte contains response ID (response type). This byte will contain 0x21.

Byte 1: ECHO

This byte is used to associate a response received from GPIO-24 adapter with a specific command. Response will contain exactly the same value in its echo byte.

Byte 2: ST

Status of the command execution:

• GPIO_ST_SUCCESS (0x00) – ADC channel configuration was succesfully configured.

Bytes 3..7: Reserved

These bytes are reserved for future usage.