83Plus:Ports:3A - Revision history

Dr. D'nar: /* TI-84+CSE */

2014-10-26T00:34:41Z

‎TI-84+CSE

Dr. D'nar: /* TI-84+CSE */

2014-10-22T07:10:26Z

‎TI-84+CSE

Dr. D'nar: /* Comments */ Changed sample routine to reflect timings specified in datasheet.

2014-10-22T06:45:39Z

‎Comments: Changed sample routine to reflect timings specified in datasheet.

Dr. D'nar: /* TI-84+CSE */ Found the datasheet for the backlight controller. It's not very interesting.

2014-10-22T06:42:48Z

‎TI-84+CSE: Found the datasheet for the backlight controller. It's not very interesting.

Dr. D'nar: /* TI-84+CSE */ Bit 4 is weird.

2014-05-15T00:11:19Z

‎TI-84+CSE: Bit 4 is weird.

KermMartian: /* Read Values */

2014-01-10T18:34:11Z

‎Read Values

KermMartian: /* Read Values */

2014-01-10T18:33:36Z

‎Read Values

Dr. D'nar: /* Synopsis */

2014-01-10T17:38:32Z

‎Synopsis

Dr. D'nar: /* TI-84+CSE */

2013-08-13T08:16:03Z

‎TI-84+CSE

Dr. D'nar: /* Comments */ I dunno, this probably works.

2013-05-10T17:08:53Z

‎Comments: I dunno, this probably works.

@@ Line 76: / Line 76: @@
 The TI-84+CSE backlight level is controlled by bit 5, which is connected to the CAT4004A Constant Current LED Driver (1-wire EZDim (TM) interface!). To turn the backlight off, reset bit 5 and leave it off. To turn the backlight on, set bit 5 and leave it on. As long as you want the backlight on, keep bit 5 set, except when you want to change the backlight level. When you turn the backlight on, it will reset to the brightest level. To reset the backlight to the brightest level, reset this bit for at least 3 ms and then turn it back on. To dim the backlight one level, reset this bit for at least 200 ns but not more than 100 µs. Each pulse will dim the backlight one level. There are 32 linearly dimming levels, from full brightness to off. Each level changes the LED's PWM dimming cycle by about 3.2 %.
-Bit 4 is weird. This is normally set to output. But when you connect a cable and the calculator starts charging, it gets changed to input.
+Bit 4 is weird. This is normally set to output. But when you connect a cable and the calculator starts charging, it gets changed to input. The charging chip is probably TI's bq2057C "Advanced linear charge management IC for single- and two-cell lithium-ion and lithium-polymer". The charge status pin reads high during charging, low when finished, and high-impedance on fault. (Is there a GPIO bit to check for a fault condition?)
 == Comments ==

@@ Line 74: / Line 74: @@
 |}
-The TI-84+CSE backlight level is controlled by bit 5, which is connected to the CAT4004A Constant Current LED Driver (1-wire EZDim (TM) interface!). To turn the backlight off, reset bit 5 and leave it off. To turn the backlight on, set bit 5 and leave it on. As long as you want the backlight on, keep bit 5 set, except when you want to change the backlight level. When you turn the backlight on, it will reset to the brightest level. To reset the backlight to the brightest level, reset this bit for at least 3 ms and then turn it back on. To dim the backlight one level, reset this bit for at least 200 ns but not more than 100 µs. Each pulse will dim the backlight one level. There are 32 levels, from full brightness to off.
+The TI-84+CSE backlight level is controlled by bit 5, which is connected to the CAT4004A Constant Current LED Driver (1-wire EZDim (TM) interface!). To turn the backlight off, reset bit 5 and leave it off. To turn the backlight on, set bit 5 and leave it on. As long as you want the backlight on, keep bit 5 set, except when you want to change the backlight level. When you turn the backlight on, it will reset to the brightest level. To reset the backlight to the brightest level, reset this bit for at least 3 ms and then turn it back on. To dim the backlight one level, reset this bit for at least 200 ns but not more than 100 µs. Each pulse will dim the backlight one level. There are 32 linearly dimming levels, from full brightness to off. Each level changes the LED's PWM dimming cycle by about 3.2 %.
 Bit 4 is weird. This is normally set to output. But when you connect a cable and the calculator starts charging, it gets changed to input.

@@ Line 91: / Line 91: @@
 	and 0DFh
 	out (3Ah), a
-	; Wait a while
+	; Set bit 5 again.
-	ld b, 80h
-	djnz $
 	; Set bit 5 again
-	in a, (3Ah)
 	or 20h
 	out (3Ah), a
 	ret</nowiki>

@@ Line 74: / Line 74: @@
 |}
-The TI-84+CSE backlight level is controlled by bit 5. To turn the backlight off, reset bit 5 and leave it off. To turn the backlight on, set bit 5 and leave it on. As long as you want the backlight on, you should keep bit 5 set, except when you want to change the backlight level. When you turn the backlight on, it will reset to the brightest level. To reset the backlight to the brightest level, reset this bit for at least 3 ms (2 seems to work, but 3 is probably safer). To dim the backlight one level, reset this bit for a few hundred clock cycles. Each pulse will dim the backlight one level. There are 32 levels, from full brightness to off.
+The TI-84+CSE backlight level is controlled by bit 5, which is connected to the CAT4004A Constant Current LED Driver (1-wire EZDim (TM) interface!). To turn the backlight off, reset bit 5 and leave it off. To turn the backlight on, set bit 5 and leave it on. As long as you want the backlight on, keep bit 5 set, except when you want to change the backlight level. When you turn the backlight on, it will reset to the brightest level. To reset the backlight to the brightest level, reset this bit for at least 3 ms and then turn it back on. To dim the backlight one level, reset this bit for at least 200 ns but not more than 100 µs. Each pulse will dim the backlight one level. There are 32 levels, from full brightness to off.
 Bit 4 is weird. This is normally set to output. But when you connect a cable and the calculator starts charging, it gets changed to input.

@@ Line 58: / Line 58: @@
 |-
 |4
-|I
+|I & O
 |Has something to do with battery charging.
 |-
@@ Line 75: / Line 75: @@
 The TI-84+CSE backlight level is controlled by bit 5. To turn the backlight off, reset bit 5 and leave it off. To turn the backlight on, set bit 5 and leave it on. As long as you want the backlight on, you should keep bit 5 set, except when you want to change the backlight level. When you turn the backlight on, it will reset to the brightest level. To reset the backlight to the brightest level, reset this bit for at least 3 ms (2 seems to work, but 3 is probably safer). To dim the backlight one level, reset this bit for a few hundred clock cycles. Each pulse will dim the backlight one level. There are 32 levels, from full brightness to off.
 == Comments ==

@@ Line 14: / Line 14: @@
 === Read Values ===
 * Bits 0-2 - Used for USB related stuff
 * Bit 3 - Set
 * Bits 4-7 - Unknown

@@ Line 27: / Line 27: @@
 === Read Values ===
 * Bits 0-3 - Reset
 * Bits 4-7 - No significance

@@ Line 9: / Line 9: @@
 This port appears to be for GPIO reading/writing. It's used for USB stuff, battery voltage testing, and on the TI-84+CSE, controlling the backlight. [[83Plus:Ports:39|Port 39h]] appears to be the GPIO setup register. More work is needed to figure out what hardware these GPIO pins interface with. This port does not exist on the TI-83+SE, which does not have any GPIO.
-On known hardware revisions for all TI-84+/C/SE, the upper four bits are wired for output and the lower four bits are for input. So, write F0 to port 39 for correct GPIO operation. Attempting to repurpose bits is unlikely to have a useful effect unless you modify the hardware. (And the OS likes to write F0 to 39 on a regular basis, so your changes won't stick long-term.)
+On known hardware revisions for all TI-84+/C/SE, the upper three bits are wired for output and the lower five bits are for input. So, write E0 to port 39 for correct GPIO operation. Attempting to repurpose bits is unlikely to have a useful effect unless you modify the hardware. (And the OS likes to write E0 to 39 on a regular basis, so your changes won't stick long-term.)
 == TI-84+/SE Old hardware ==

@@ Line 56: / Line 56: @@
 |-
 |4
-|O
+|I
-|Unknown
+|Has something to do with battery charging.
 |-
 |5