LPC11u24 Programming Circuit - Page 1
Forum section: electronics / general

author: MattHollands
author_rank: Frequent Contributor
timestamp: December 30, 2016, 10:44:37 pm
content: I am working on a system that uses an LPC11u24 as its processor. Previously I've always used Atmel 8 bit AVRs so this is my first foray into ARMs. However I can't really find much in the datasheet about programming - I think I just need the SWDIO and SWCLK pins and the RESET line but I'm not confident in that. I have messed around with the MBED platform, but that's a bit convoluted because it uses the MBED interface chip to program the device instead of using a SWD/JTAG programmer.If anyone has experience with this chipset, could you please verify that I am doing the right thing here, specifically with the Cortex 10-pin connector and also with the USB interface!Much appreciated!Matt

author: nctnico
author_rank: Super Contributor
timestamp: December 30, 2016, 10:55:09 pm
content: I'd break out the serial port as well so you can fall back on serial port programming using a simple USB-UART board with DTR and CTS lines and the Flashmagic software. The flash section in the user manual tells you which pin needs to be held low for the bootloader to enter into serial programming mode.

author: ataradov
author_rank: Super Contributor
timestamp: December 30, 2016, 10:56:19 pm
content: 1. SWCLK had to be pulled up.2. Your connector is really strange. On a standard connector pin 9 is GNDDetect and pin 7 is KEY (unused). And pin 8 is TDI, and SWO / TDO is pin 6.Otherwise this looks OK.

author: MattHollands
author_rank: Frequent Contributor
timestamp: December 30, 2016, 11:08:35 pm
content: Quote from: ataradov on December 30, 2016, 10:56:19 pmRegarding point 1, I've read a load of contradictory things on this. For example, onhttps://www.lpcware.com/content/forum/lpc1778-swd-swclk-pull-or-pull-downlpcxpresso-support says that a pull-down is recommended. It sort of looks like it doesn't matter if you use pull-up or down.Regarding point 2.... Yeah I don't know what I've done there. I guess I can't count to 10.

author: ataradov
author_rank: Super Contributor
timestamp: December 30, 2016, 11:16:42 pm
content: Quote from: MattHollands on December 30, 2016, 11:08:35 pmWell, the only authoritative document on this is a user manual, and it says:QuoteBoth pins are already pulled-up as this is the default bus state according to ARM. External pull-up resistors are used for improved EMI resistance, but are not strictly necessary.

author: MattHollands
author_rank: Frequent Contributor
timestamp: December 30, 2016, 11:28:23 pm
content: Quote from: ataradov on December 30, 2016, 11:16:42 pmFair enough. To be honest, I didn't realise there was a user manual - I had just been looking at the data sheet. I did think there was a lot of information missing.Quote from: nctnico on December 30, 2016, 10:55:09 pmGood idea. It seems like RX and TX etc can be multiplexed to multiple pins... does it matter which one I use?

author: ataradov
author_rank: Super Contributor
timestamp: December 30, 2016, 11:30:17 pm
content: Quote from: MattHollands on December 30, 2016, 11:28:23 pmUser Manual to the rescue:QuoteBut read the whole section "20.2 Bootloader", it has a lot of relevant stuff.

author: MattHollands
author_rank: Frequent Contributor
timestamp: December 31, 2016, 12:05:07 am
content: Oh man. I need to get used to their datasheet layout. Thanks for your help!

author: ataradov
author_rank: Super Contributor
timestamp: December 31, 2016, 12:07:57 am
content: Quote from: MattHollands on December 31, 2016, 12:05:07 amWith NXP I just skip the datasheet part and go straight to the UM. This is annoying, but noting you can do about it.Atmel used to have full datasheets and summary datasheets. Same idea - one is useful, the other one is pointless. But they stopped doing that for new parts, and now there is only one document that has all the information.

author: nctnico
author_rank: Super Contributor
timestamp: December 31, 2016, 12:24:09 am
content: Quote from: ataradov on December 31, 2016, 12:07:57 amI disagree. The datasheet has the electrical specifications and the user manual has the functional specifications. Mixing those just makes things less clear. You'll need both though to get a NXP ARM controller up & running.Nowadays many complex chips have seperate datasheets, user manuals and errata sheet so go through all these document to get a complete picture.

author: Jeroen3
author_rank: Super Contributor
timestamp: January 05, 2017, 08:33:25 am
content: Quote from: nctnico on December 30, 2016, 10:55:09 pmNo need. This chip has USB MSC bootloader built-in.