CTS not being asserted on uart1 of my NanoPI NEO Air
Posted: Sun Apr 22, 2018 6:31 pm
I have been testing serial connectivity on my NanoPi NEO Air to a u-blox GSM LEON G100 device connected to uart1
Linux NanoPi-NEO-Air 4.11.0-rc4 #100 SMP Thu May 18 17:59:49 CST 2017 armv7l armv7l armv7l GNU/Linux
At first I thought the problem was with my software, I then decided to test with both minimum and picocom with hardware handshaking enabled... still no luck!
If I do a cross-over of RTS <-> CTS on the u-blox side then everything works!
This leads me to believe CTS is not being asserted on uart1 when the u-blox raises RTS
doing a gpio readall these are my results:
Code: Select all
+-----+-----+----------+------+---+-NanoPi NEO/NEO2--+------+----------+-----+-----+
| BCM | wPi | Name | Mode | V | Physical | V | Mode | Name | wPi | BCM |
+-----+-----+----------+------+---+----++----+---+------+----------+-----+-----+
| | | 3.3V | | | 1 || 2 | | | 5V | | |
| 12 | 8 | GPIOA12 | ALT5 | 0 | 3 || 4 | | | 5V | | |
| 11 | 9 | GPIOA11 | ALT5 | 0 | 5 || 6 | | | 0v | | |
| 203 | 7 | GPIOG11 | OFF | 0 | 7 || 8 | 0 | ALT5 | GPIOG6 | 15 | 198 |
| | | 0v | | | 9 || 10 | 0 | ALT5 | GPIOG7 | 16 | 199 |
| 0 | 0 | GPIOA0 | OFF | 0 | 11 || 12 | 0 | OFF | GPIOA6 | 1 | 6 |
| 2 | 2 | GPIOA2 | OFF | 0 | 13 || 14 | | | 0v | | |
| 3 | 3 | GPIOA3 | OFF | 0 | 15 || 16 | 0 | OFF | GPIOG8 | 4 | 200 |
| | | 3.3v | | | 17 || 18 | 0 | OFF | GPIOG9 | 5 | 201 |
| 64 | 12 | GPIOC0 | ALT4 | 0 | 19 || 20 | | | 0v | | |
| 65 | 13 | GPIOC1 | ALT4 | 0 | 21 || 22 | 0 | OFF | GPIOA1 | 6 | 1 |
| 66 | 14 | GPIOC2 | ALT4 | 0 | 23 || 24 | 0 | ALT4 | GPIOC3 | 10 | 67 |
+-----+-----+----------+------+---+----++----+---+------+----------+-----+-----+
| BCM | wPi | Name | Mode | V | Physical | V | Mode | Name | wPi | BCM |
+-----+-----+----------+------+---+-NanoPi NEO/NEO2--+------+----------+-----+-----+
Questions:
1. Why does GPIOG8 show as off?
2. What is the difference between modes ALT4/5 and how do I enable them? (or is it implied?)
3. Is the schematic on page 5 for uart1 rts/cts incorrect? see here: https://screencast.com/t/lHuI5Xy2ta8
Linux NanoPi-NEO-Air 4.11.0-rc4 #100 SMP Thu May 18 17:59:49 CST 2017 armv7l armv7l armv7l GNU/Linux
At first I thought the problem was with my software, I then decided to test with both minimum and picocom with hardware handshaking enabled... still no luck!
If I do a cross-over of RTS <-> CTS on the u-blox side then everything works!
This leads me to believe CTS is not being asserted on uart1 when the u-blox raises RTS
doing a gpio readall these are my results:
Code: Select all
+-----+-----+----------+------+---+-NanoPi NEO/NEO2--+------+----------+-----+-----+
| BCM | wPi | Name | Mode | V | Physical | V | Mode | Name | wPi | BCM |
+-----+-----+----------+------+---+----++----+---+------+----------+-----+-----+
| | | 3.3V | | | 1 || 2 | | | 5V | | |
| 12 | 8 | GPIOA12 | ALT5 | 0 | 3 || 4 | | | 5V | | |
| 11 | 9 | GPIOA11 | ALT5 | 0 | 5 || 6 | | | 0v | | |
| 203 | 7 | GPIOG11 | OFF | 0 | 7 || 8 | 0 | ALT5 | GPIOG6 | 15 | 198 |
| | | 0v | | | 9 || 10 | 0 | ALT5 | GPIOG7 | 16 | 199 |
| 0 | 0 | GPIOA0 | OFF | 0 | 11 || 12 | 0 | OFF | GPIOA6 | 1 | 6 |
| 2 | 2 | GPIOA2 | OFF | 0 | 13 || 14 | | | 0v | | |
| 3 | 3 | GPIOA3 | OFF | 0 | 15 || 16 | 0 | OFF | GPIOG8 | 4 | 200 |
| | | 3.3v | | | 17 || 18 | 0 | OFF | GPIOG9 | 5 | 201 |
| 64 | 12 | GPIOC0 | ALT4 | 0 | 19 || 20 | | | 0v | | |
| 65 | 13 | GPIOC1 | ALT4 | 0 | 21 || 22 | 0 | OFF | GPIOA1 | 6 | 1 |
| 66 | 14 | GPIOC2 | ALT4 | 0 | 23 || 24 | 0 | ALT4 | GPIOC3 | 10 | 67 |
+-----+-----+----------+------+---+----++----+---+------+----------+-----+-----+
| BCM | wPi | Name | Mode | V | Physical | V | Mode | Name | wPi | BCM |
+-----+-----+----------+------+---+-NanoPi NEO/NEO2--+------+----------+-----+-----+
Questions:
1. Why does GPIOG8 show as off?
2. What is the difference between modes ALT4/5 and how do I enable them? (or is it implied?)
3. Is the schematic on page 5 for uart1 rts/cts incorrect? see here: https://screencast.com/t/lHuI5Xy2ta8