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@@ -4,6 +4,7 @@ ToC:
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- Introduction
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- Booting
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- Debugging
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+- i2c
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Introduction
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@@ -130,3 +131,56 @@ dongle from Olimex successfully as follows:
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# openocd \
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-f interface/ftdi/olimex-arm-usb-ocd-h.cfg \
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-f board/phytec_lpc3250.cfg
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+
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+
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+i2c
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+===
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+Some of the LEDs on the board are connected via an I/O Expander (PCA9532) that
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+is attached to the i2c1 bus. Here is a sample session of toggling some of
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+these LEDs via i2c in U-Boot:
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+
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+show the existing i2c busses:
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+ EA-LPC3250v2=> i2c bus
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+ Bus 0: i2c@300
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+ Bus 1: i2c@400a0000
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+ Bus 2: i2c@400a8000
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+
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+set i2c1 as the current bus:
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+ EA-LPC3250v2=> i2c dev 1
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+ Setting bus to 1
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+
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+see what potential devices are found with rudimentary probing on i2c1:
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+ EA-LPC3250v2=> i2c probe
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+ Valid chip addresses: 1A 1D 48 50 57 60 66 6E
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+
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+According to the schematics the i2c slave address of the PCA9532 is 0x60.
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+
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+dump all of the 10 registers from the I/O Expander; NOTE that the 0x10 in the
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+command specifies the self-incrementing mode of the PCA9532; also NOTE that
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+the values repeat themseves to fill out a full 16 bytes:
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+ EA-LPC3250v2=> i2c md 0x60 0x10 10
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+ 0010: 00 ff 00 80 00 80 00 00 00 00 4f ff 00 80 00 80 ..........O.....
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+
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+turn on LEDs 23, 25, 27, and 29 (green):
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+ EA-LPC3250v2=> i2c mw 0x60 9 0x55
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+
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+turn on LEDs 22, 24, 26, and 28 (red):
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+ EA-LPC3250v2=> i2c mw 0x60 8 0x55
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+
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+dim the green LEDs (23, 25, 27, 29):
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+ EA-LPC3250v2=> i2c mw 0x60 3 0x20
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+ EA-LPC3250v2=> i2c mw 0x60 9 0xaa
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+
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+turn off all LEDs (23-29):
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+ EA-LPC3250v2=> i2c mw 0x60 8 0
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+ EA-LPC3250v2=> i2c mw 0x60 9 0
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+
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+read value of switches (input):
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+ EA-LPC3250v2=> i2c md 0x60 0 1
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+ 0000: 4f O
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+[none are pressed]
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+
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+press and hold SW2 while running the following:
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+ EA-LPC3250v2=> i2c md 0x60 0 1
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+ 0000: 4e N
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+[SW2 is pressed]
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