CALIBRE
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| When all the bytes have been transmitted a stop is issued and the total | |||
| number of bytes is returned. | |||
| Sendbytes can only be used in master write mode. | |||
4.4.13. getbytes |
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Function specification | Int getbytes(int far *transferarray) | |||
Parameters are: | int far *transferarray | |||
| The far pointer must point to a single dimensional array the format of which is | |||
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| The calling function must have initialised elements 0, 1 and 2 prior to calling | |||
| the function. |
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Element no | Element name | Description | ||
0 | slaveaddress | Slaveaddress is the address to be accessed via the | ||
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| I2C Bus, this is in hexadecimal e.g. A0H. | ||
1 | wordaddress | Wordaddress is the offset within the slave to which | ||
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| the first byte of data is to be written, see | ||
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| transmission format for more detail. | ||
2 | nobytes | The number of bytes (n) to be sent. Min value 1. | ||
3 | byte 0 | First byte read. | ||
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| byte n | Last byte read. | ||
Parameters returned | int nobytesread |
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| The number of bytes actually read. | |||
Prerequisites | Adapter must be configured using setup. Array elements 0, 1 and 2 must be | |||
| initialised. Elements 3 to n do not need to be initialised since they are where | |||
| the read data is returned. The array must be | |||
| large enough to hold all the parameters and data concerned. | |||
Transmission Format | If the slaveaddress has the least significant bit set (1) then this forms a read | |||
| address, if the least significant bit is clear (0) then this forms the write | |||
| address e.g. A0H is the write address and A1H is the associated read | |||
| address. |
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getbytes supports two transfer formats these being:
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To select transfer format i) pass the read address as slaveaddress. The wordaddress is not used in this format and is ignored by getbytes.
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To select transfer format ii) pass the write address as slaveaddress. In this format the wordaddress must be valid.
wordaddress is pointer to the first byte of data to be read.
nobytestoread is the number of bytes to be read. The minimum value allowable is 1.
Issue 1.3 | Page 25 |
22/07/99