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authorBenedikt Otto <beneot@web.de>2020-07-25 13:27:51 +0200
committerGerhard Sittig <gerhard.sittig@gmx.net>2020-08-30 10:46:24 +0200
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mcp23017: Add dumps of the microchip mcp23017 i/o expander
[ gsi: minor README markup/flow nits, more perceivable chip function ]
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+-------------------------------------------------------------------------------
+Microchip MCP23017 I/O expander with I2C interface
+-------------------------------------------------------------------------------
+
+This is a set of example captures of the MCP23017 16-bit I/O expander with
+an I2C interface. For details see the MCP23017/MCP23S17 datasheet which is
+titled "16-Bit I/O Expander with Serial Interface":
+
+ http://ww1.microchip.com/downloads/en/DeviceDoc/20001952C.pdf
+
+
+Logic analyzer setup
+--------------------
+
+The logic analyzer used was a Saleae clone (samplerate 1MHz). In addition
+to the I2C datalines, 6 output pins are captured too.
+
+The host was a Raspberry Pi using Python to access the I2C port. The bitrate
+decreased after a few 100ms.
+
+ Probe MCP23017
+ -------------------
+ 0 A0
+ 1 A1
+ 2 A2
+ 3 B0 / A3
+ 4 B1 / A4
+ 5 B2 / A5
+ 6 SDA
+ 7 SCL
+
+
+mcp23017_counter_a_write.sr
+---------------------------
+
+Count the Registers OLATA ascending. The lowest 6 bits of the Output A Port
+are captured too (A0 - A5).
+
+
+mcp23017_counter_init_ab_write.sr
+---------------------------------
+
+Reset all registers, then count the registers OLATA ascending and OLATB
+descending. Both registers are set using one word write operation. The
+lowest 3 bits of both output ports are captured too (A0 - A2, B0 - B2).
+
+
+mcp23017_counter_init_ab_write_read.sr
+-------------------------------------
+
+Reset all registers, then count the registers OLATA ascending and OLATB
+descending. Both registers are set and read using one word write operations.
+The lowest 3 bits of both output ports are captured too (A0 - A2, B0 - B2).